Dr. Stephan Streuber holds a Diploma in Media Informatics from Harz University of Applied Sciences and a PhD in Neural and Behavioral Sciences from the Max Planck Institute for Biological Cybernetics in Tübingen, Germany (2013), supported by a Research Fellowship from the Max Planck Society. He later held research positions at the Max Planck Institute for Intelligent Systems and the Brain Mind Institute at EPFL in Lausanne, Switzerland.

In 2018, he joined the University of Konstanz as an Assistant Professor for Virtual Reality and Collective Behavior, a role he held until 2021. Since then, he has been a Full Professor of Usability Engineering and Interaction Design in Visual Computing at Coburg University of Applied Sciences and Arts, where he leads the Virtual Environments and Social Interaction Lab (socialVRlab.com).

His main research aim is to understand the mechanisms behind social interactions. To do this, he creates immersive multi-user virtual environments with realistic avatars and AI-powered agents, facilitating the study of group coordination, synchronization, and emotion contagion. His work also investigates body perception and representation, with clinical applications in eating disorders, stroke rehabilitation, and XR-based mental health research and treatment.

1. When the Average Hides the Signal: Graph Theory and Sex Differences in HRV

Publication: Biology of Sex Differences

Authors: Lin Sørensen, Elisabet Kvadsheim, Julian Koenig, Julian F Thayer, DeWayne P Williams, Hayley Jessica MacDonald, Ryan Douglas McCardle, Daniel Wollschlaeger, Ole Bernt Fasmer, Berge Osnes

KEY FINDING:

In 269 healthy young adults, a similarity graph theory algorithm detected significant sex differences in nonlinear inter-beat interval variability — males showing higher graph metric values, indicating lower dynamic IBI fluctuations — while standard measures lnRMSSD and lnHF-HRV failed to distinguish sexes when used alone. The odds ratio for the graph metric predicting sex was 2.78 (95% CI: 1.32–5.86).

SIGNIFICANCE:

Conventional averaged HRV metrics may systematically underdetect sex-based autonomic differences that exist in the rapid, nonlinear structure of beat-to-beat activity. Nonlinear graph-theoretic approaches offer a complementary analytical lens that could refine how sex is accounted for in autonomic research and in clinical HRV norms.

→ Read full study: https://www.researchgate.net/publication/403769793_Capturing_sex_differences_in_spontaneous_autonomic_fluctuations_of_resting_heart_rate_using_a_similarity_graph_theory_approach

2. Why Your GLP-1 Medication Raises Your Heart Rate: A Neural Explanation

Publication: Hypertension Research

Authors: Yui Koyanagi, Kamon Iigaya, Keiko Ikeda, Hiroshi Onimaru, Masahiko Izumizaki

KEY FINDING:

Exendin-4, a major GLP-1 receptor agonist, increased sympathetic nerve activity and produced membrane depolarization in preganglionic neurons of the spinal cord and neurons in the rostral ventrolateral medulla in vitro. The effect was blocked by a GLP-1 receptor antagonist, confirming receptor-mediated sympathetic excitation at both spinal and brainstem levels.

SIGNIFICANCE:

This study provides the clearest mechanistic evidence to date that GLP-1 receptor agonists can directly excite sympathetic neurons — offering a plausible neural explanation for the heart rate increases commonly observed in patients on this medication class. For practitioners monitoring autonomic function in patients on GLP-1 therapies, this finding provides important physiological context.

→ Read full study: https://www.nature.com/articles/s41440-026-02633-5

3. Two Systems Failing Together: HRV and Nerve Conduction in Early Diabetes

Publication: Cureus

Authors: Anwar H. Siddiqui, Md S. Alam, Ahmad Faraz, Nazia Tauheed, Hamid Ashraf, SAA Rizvi

KEY FINDING:

In 100 patients with type 2 diabetes of less than 5 years' duration, compared with 100 matched controls, parasympathetic HRV indices and peripheral nerve amplitudes were both significantly reduced in the diabetes group, with the strongest single correlation between high-frequency HRV power and sural SNAP amplitude (r = 0.62). Multivariable regression identified higher HbA1c and longer diabetes duration — not age, sex, or BMI — as the independent predictors of HRV impairment.

SIGNIFICANCE:

Cardiac autonomic and peripheral nerve dysfunction appear to develop in parallel in early-stage type 2 diabetes, sharing common metabolic drivers. This cross-sectional study cannot establish causality, but the findings support the potential value of combined HRV and nerve conduction assessment for detecting subclinical neuropathy early, when metabolic intervention may still alter the trajectory.

→ Read full study: https://www.cureus.com/articles/466542-association-between-cardiac-autonomic-function-and-peripheral-nerve-conduction-abnormalities-in-type-2-diabetes-mellitus-a-cross-sectional-study#!/

4. Can HRV Predict an Autonomic Storm? Early Evidence from Brain Injury Patients

Publication: Clinical Autonomic Research

Authors: Francesco Riganello, Maria D. Cortese, Martina Vatrano, Lucia F. Lucca, Maria E. Pugliese, Maria Ursino, Elio Leto, Antonio Cerasa, Nicholas Schiff, Andrea Soddu

KEY FINDING:

In six patients with disorders of consciousness, HRV analysis preceding paroxysmal sympathetic hyperactivity episodes showed reduced entropy complexity and decreased power in both low- and high-frequency bands, alongside an elevated VLF/(LF+HF) ratio. A support vector machine classifier achieved 67% sensitivity, 100% specificity, and 83% balanced accuracy in predicting episode onset ten minutes in advance.

SIGNIFICANCE:

This proof-of-concept study demonstrates that HRV signals carry detectable autonomic signatures before paroxysmal sympathetic hyperactivity episodes occur. The six-patient sample and the absence of external validation require caution in interpreting these performance figures, but the work establishes a meaningful foundation for investigating machine learning-based predictive monitoring in this high-stakes clinical context.

→ Read full study: https://link.springer.com/article/10.1007/s10286-025-01175-z

5. The Quiet Signal: VLF Heart Rate Variability as an Inflammatory Marker in Healthy Adults

Publication: Autonomic Neuroscience

Authors: Usui Harunobu

KEY FINDING:

In 26 healthy young adults using a multiday 24-hour HRV monitoring protocol, LnVLF showed a strong positive association with LnIL-6 (Bayes factor = 18.61), with 95% credible intervals entirely above zero. Neither the HF nor LF components showed evidence of association with either IL-6 or hs-CRP. LnVLF remained an independent predictor of LnIL-6 after adjusting for BMI and daily step count.

SIGNIFICANCE:

This is the first study to establish a robust association between VLF heart rate variability and interleukin-6 specifically in healthy young adults using a rigorous Bayesian and multiday measurement framework. The findings position VLF as a potentially useful noninvasive indicator of low-grade inflammatory burden in healthy populations — a direction that warrants further replication in larger, more diverse samples.

→ Read full study: https://www.sciencedirect.com/science/article/abs/pii/S156607022600041X

6. Fit Heart, Variable Heart: HRV and VO2 Max in High-Risk Patients

Publication: Acta Cardiologica Sinica

Authors: Selin Cilli Hayiroğlu, Mehmet Uzun

KEY FINDING:

In 311 asymptomatic individuals with high cardiovascular risk, VO2 max correlated significantly with total power, LF, HF, rMSSD, and SDNN index after age adjustment, with the strongest association for HF (rho = 0.360, p < 0.001). VO2 max independently predicted 5-year major adverse cardiac events (HR 0.833, 95% CI: 0.783–0.887), while none of the HRV parameters showed independent prognostic significance in the adjusted model.

SIGNIFICANCE:

This cross-sectional, retrospective study demonstrates that HRV and aerobic fitness are meaningfully correlated in high-risk asymptomatic patients, with parasympathetic indices most strongly aligned with VO2 max. The dissociation between HRV's correlation with fitness and its lack of independent prognostic value suggests HRV functions as a parallel marker of autonomic regulation rather than a mediator of cardiovascular risk — an important distinction for how practitioners interpret and apply HRV data in this group.

→ Read full study: https://doi.org/10.6515/ACS.202603_42(2).20250725A

Key Themes

• Standard averaged HRV metrics may miss sex-based autonomic differences that live in the rapid, nonlinear structure of beat-to-beat activity — nonlinear analytical tools are increasingly necessary
• GLP-1 receptor agonists appear to excite sympathetic neurons directly at both spinal and brainstem levels, providing a plausible neural mechanism for the elevated heart rate widely observed in clinical practice
• In early type 2 diabetes, cardiac autonomic and peripheral nerve dysfunction develop in parallel and share metabolic predictors — a combined neurophysiological assessment may improve early detection
• Machine learning applied to HRV data shows proof-of-concept promise for predicting paroxysmal sympathetic hyperactivity episodes, though rigorous external validation in larger samples is essential before clinical application
• VLF heart rate variability may carry meaningful information about the inflammatory state in healthy young adults — the least understood HRV frequency band deserves closer attention

SPONSORED BY OPTIMAL HRV

Optimal HRV is the most comprehensive HRV platform built for practitioners, researchers, and health-focused individuals who want to go beyond basic tracking. With tools for daily monitoring, longitudinal analysis, and population-level insights, Optimal HRV gives you the depth to truly understand your data. Visit optimalhrv.com to learn more.

The content in this episode is for educational and informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider regarding any health concerns or before making changes to your health regimen.

This week's episode covers four studies across four completely different clinical domains — acupuncture, exercise physiology, sleep medicine, and urology — and finds the same thread running through them all: HRV as a window into autonomic regulation. Whether the stimulus is a needle, a treadmill, an overnight wearable patch, or a surgical instrument, the nervous system responds in ways HRV can detect. Episode 33 explores what that means for practice, research, and the expanding frontier of autonomic science.

Research Highlights This Week

Mapping Ancient Points onto Modern Mechanisms: The Case for a Biomedical Acupuncture Framework

Publication: Cureus

Authors: Yiangos Karavis, Miltiades Karavis

KEY FINDING: A structured narrative review of 71 studies found convergent mechanistic evidence for a candidate cluster of acupuncture points — including ST36, PC6, LI4, SP6, LR3, and GV20 — across autonomic modulation, neuroimmune signaling, and HRV outcomes. ST36 and PC6 were repeatedly associated with vagal pathway activation and increased high-frequency HRV, while multiple points suppressed pro-inflammatory cytokines and modulated nuclear factor kappa B and NOD-like receptor thermal protein domain-associated protein 3 inflammasome signaling.

SIGNIFICANCE: This review offers one of the most systematic attempts to translate traditional acupuncture point designations into a biomedically grounded teaching framework. While prospective validation is still required, the mechanistic convergence across independent studies suggests that peripheral stimulation at specific anatomical sites can engage autonomic and neuroimmune circuits in measurable ways — with real implications for integrative practice, pain medicine, and HRV research.

Read full study: https://doi.org/10.7759/cureus.106511

Six Weeks on the Treadmill: Autonomic Recovery in Sedentary Obese Young Adults

Publication: Journal of Datta Meghe Institute of Medical Sciences University

Authors: Subha Shankar Sahoo, Shivani Patil, M. Premkumar

KEY FINDING: Forty-one sedentary obese adults aged 17–25 completed a 6-week moderate-intensity treadmill program. By 45 days, all measured HRV parameters — the standard deviation of normal-to-normal intervals, the standard deviation of normal-to-normal intervals index, high-frequency power, low-frequency power, and very low-frequency power — improved significantly (p < 0.001). Resting and minimum heart rates decreased, systolic blood pressure dropped, and peak exercise heart rate increased, suggesting improved chronotropic competence alongside enhanced vagal tone.

SIGNIFICANCE: This study provides time-resolved evidence that a practical, moderate-intensity exercise program can produce measurable autonomic improvements in a population with common dysregulation. The gains in high-frequency HRV point specifically toward enhanced vagal tone. While the pre–post design without a control group limits causal conclusions, the direction and magnitude of effects are clinically encouraging for practitioners using exercise as an autonomic rehabilitation tool.

Read full study: https://doi.org/10.4103/jdmimsu.jdmimsu_731_25

From Snoring to Signal: Using a Wearable HRV Patch and Artificial Intelligence to Screen for Sleep Apnea

Publication: Nature and Science of Sleep

Authors: Ying-Shuo Hsu, Yu-Cheng Lin, Yu-En Kuo, Cheng-Han Chou, Mei-Chun Chou, Yi Chang, Ofer Jacobowitz, Chia-Mo Lin, Shih-Chieh Lo, Terry BJ Kuo, Cheryl CH Yang

KEY FINDING: A chest-worn patch-type HRV analyzer combined with an artificial intelligence model achieved 81.4% accuracy in screening for moderate-to-severe obstructive sleep apnea — outperforming demographic-based screening (73%) and a previous electrocardiogram patch method (70.6%). The best-performing model incorporated nonlinear HRV features and electrocardiogram R-S amplitude data into a novel composite index called the Cardiovascular Hypopnea Index, with an area under the receiver operating characteristic curve of 0.81 at an apnea-hypopnea index cutoff of 15.

SIGNIFICANCE: This study demonstrates that a single-channel wearable cardiac device, when combined with comprehensive nonlinear HRV analysis and artificial intelligence, can meaningfully detect moderate-to-severe obstructive sleep apnea at home — without the complexity and discomfort of multi-sensor monitoring systems. The finding that nonlinear HRV complexity metrics outperform standard time-domain and frequency-domain measures underscores the diagnostic information that remains underexplored in the cardiac signal.

Read full study: https://doi.org/10.2147/NSS.S568569

The Prostate and the Nervous System: HRV as a Marker of Autonomic Recovery After Benign Prostatic Hyperplasia Treatment

Publication: Life

Authors: Kuan-Yu Chen, Yu-Hui Huang, Yun-Sheng Chen, Min-Hsin Yang, Kai-Siang Chen, Chieh-Jui Chen, Cheng-Ju Ho, Chih-Kai Peng, Sung-Lang Chen

KEY FINDING: In an observational study of 452 men with benign prostatic hyperplasia and bladder outlet obstruction, transurethral resection of the prostate was associated with significantly greater HRV restoration than tamsulosin at 12 weeks. The standard deviation of normal-to-normal intervals increased by ~40% after surgery, compared with ~18% with medication; the low-frequency-to-high-frequency ratio decreased by 55% after surgery, compared with 8% with medication; and total power nearly doubled in the surgical group. A change in the standard deviation of normal-to-normal intervals independently predicted urinary symptom improvement in multivariate regression (standardized beta = −0.42, accounting for 28% of the variance).

SIGNIFICANCE: This study reframes benign prostatic hyperplasia as a condition with systemic autonomic consequences rather than solely urological ones. The greater HRV restoration after surgical obstruction relief compared to pharmacological blockade supports the hypothesis that chronic mechanical obstruction generates afferent autonomic stress, and that HRV can track its resolution. These are hypothesis-generating findings requiring randomized trial confirmation, but they open an important new avenue for understanding visceral obstruction and autonomic health.

Read full study: https://doi.org/10.3390/life16040600

Key Themes This Week

• HRV as a cross-domain marker: Four studies from entirely different clinical fields — integrative medicine, exercise physiology, sleep medicine, and urology — all used HRV to detect autonomic changes, reinforcing its value as a universal physiological readout
• Vagal activation is the consistent direction of benefit: High-frequency HRV and parasympathetic markers improved across all four studies, regardless of whether the intervention was a needle, exercise, an artificial intelligence screening tool, or surgery
• Nonlinear HRV carries information that standard measures miss: The sleep apnea study demonstrated that combining nonlinear complexity metrics with electrocardiogram amplitude data — and applying artificial intelligence — dramatically improves screening accuracy over standard HRV analysis alone
• Chronic physiological stress dysregulates autonomics beyond the affected organ: Obesity-related sedentarism and bladder outlet obstruction both imposed measurable systemic autonomic burdens — reinforcing that HRV reflects whole-body regulatory state, not just cardiovascular fitness
• All four studies call for further validation: Prospective trials, larger samples, external validation, and randomized designs are needed across the board before any of these findings should drive direct clinical practice change

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This content is for educational and informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for guidance specific to your health situation.

Polyvagal Theory has profoundly shaped how clinicians, trauma survivors, and the HRV community understand the relationship between the nervous system, safety, and social engagement. However, as the theory has moved from academic psychophysiology into the cultural mainstream, it has faced increasing scrutiny from the scientific community.

Today, we break down the history of the theory, the core of the scientific disagreement, and what this means for the future of HRV interpretation.

The Evolution of a Theory

Polyvagal Theory did not appear overnight. It evolved through decades of work by Dr. Stephen Porges, moving from specific observations about cardiac regulation to a broad "science of safety."

• 1980s–Early 1990s: Porges focuses on Respiratory Sinus Arrhythmia (RSA) as a window into the vagal regulation of the heart.

• 1995: Formal introduction of Polyvagal Theory, arguing that the vagus system consists of different pathways with distinct functional roles.

• 2001: The framework expands to include the "Social Nervous System," highlighting the phylogenetic shift in mammals toward social engagement as a regulatory strategy.

• 2011–Present: The theory becomes a cornerstone of trauma-informed care, introducing concepts like neuroception and the vagal brake.

The Core of the Controversy: Two Perspectives

The debate reached a fever pitch in 2026 following a major critical evaluation by Paul Grossman and 38 coauthors, followed by a direct rebuttal from Porges. The disagreement spans three primary domains:

1. The Interpretation of RSA and HRV

• The Critique: Critics argue that RSA is not a "pure" measure of cardiac vagal tone. Factors like breathing rate, depth, age, and baroreflex dynamics make it impossible to treat RSA as a direct readout of the "ventral vagus."

• The Defense: Porges argues the theory doesn't claim RSA is a global measure of total vagal tone, but a context-sensitive index of a specific, functional cardioinhibitory pathway.

2. The Dorsal vs. Ventral Vagus Distinction

• The Critique: Anatomists argue that the "ladder" of autonomic states is oversimplified. They suggest the Dorsal Motor Nucleus does not play the primary role in human "shutdown" or "fainting" states, as the theory suggests.

• The Defense: Porges maintains that the theory describes functional reorganization and state-dependent recruitment, rather than a rigid anatomical switch.

3. The Evolutionary Timeline

• The Critique: Evolutionary biologists point out that many "mammalian" traits (complex sociality, myelinated vagal fibers) are also found in reptiles, challenging the theory’s phylogenetic claims.

• The Defense: Porges clarifies that the claim is about the integration of these systems—specifically, how mammals coordinated the vagus with cranial nerves to support co-regulation.

Key Takeaways for the HRV Community

• Interpretation requires humility: A single HRV or RSA value cannot be used as a definitive "safety meter."

• Context is everything: Respiration and activity significantly influence the signal.

• Clinical utility vs. Mechanistic accuracy: A theory can be a powerful tool for healing even while its underlying biological mechanisms are being refined.

References

Doody, J. S., Burghardt, G. M., & Dinets, V. (2023). The evolution of sociality and the polyvagal theory. Biological Psychology, 180, 108569.

Grossman, P. (2023). Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory. Biological Psychology, 180, 108589.

Grossman, P., & Taylor, E. W. (2007). Toward understanding respiratory sinus arrhythmia: Relations to cardiac vagal tone, evolution, and biobehavioral functions. Biological Psychology, 74(2), 263-285.

Grossman, P., et al. (2026). Why the polyvagal theory is untenable: An international expert evaluation of the polyvagal theory and commentary upon Porges, S. W. (2025). Clinical Neuropsychiatry, 23(1), 100-112.

Karemaker, J. M. (2022). The multibranched nerve: Vagal function beyond heart rate variability. Biological Psychology, 172, 108378.

Neuhuber, W. L., & Berthoud, H.-R. (2022). Functional anatomy of the vagus system: How does the polyvagal theory comply? Biological Psychology, 174, 108425.

Porges, S. W. (1995). Orienting in a defensive world: Mammalian modifications of our evolutionary heritage. A polyvagal theory. Psychophysiology, 32(4), 301-318.

Porges, S. W. (2001). The polyvagal theory: Phylogenetic substrates of a social nervous system. International Journal of Psychophysiology, 42(2), 123-146.

Porges, S. W. (2011). The polyvagal theory: Neurophysiological foundations of emotions, attachment, communication, and self-regulation. W. W. Norton & Company.

Porges, S. W. (2025). Polyvagal theory: Current status, clinical applications, and future directions. Clinical Neuropsychiatry, 22(3), 169-184.

Porges, S. W. (2026). When a critique becomes untenable: A scholarly response to Grossman et al.'s evaluation of polyvagal theory. Clinical Neuropsychiatry, 23(1), 113-128.

Sponsored by Optimal HRV

This episode is sponsored by Optimal HRV.

In a field where interpretation is everything, long-term patterns matter. Optimal HRV provides tools for structured assessments and resonance-frequency breathing to help you see the "big picture" of autonomic resilience.

Learn more: https://optimalhrv.com

Medical Disclaimer

This podcast is for educational and informational purposes only. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional.

1. Real or Placebo? Putting HRV Biofeedback to the Test

Minjoz and colleagues published a randomized controlled trial in Biological Psychology comparing genuine HRV biofeedback against a convincing sham condition in 47 healthy adults.

Key Findings: HRV biofeedback improved positive affectivity and reduced depression significantly more than the sham condition. However, no significant differences in HRV itself were detected between groups, and higher HRV during practice did not reliably predict greater psychological benefit.

Significance: The psychological benefits of HRV biofeedback are real and exceed those of a placebo, but the mechanism may not be HRV changes themselves. This challenges practitioners to be more precise about how and why they recommend this intervention.

Study Link: View Article

2. Your Thinking Brain Has Its Own HRV Signature

Mao, Okutomi, and Umeno published a study in Scientific Reports comparing time-domain, frequency-domain, and chaos and complexity HRV indices during both physical and mental tasks.

Key Findings: During mental tasks, conventional HRV metrics — RMSSD, LF, HF — showed no significant changes. But chaos and complexity indices increased significantly, marking cognitive engagement with a unique nonlinear fingerprint.

Significance: The brain-heart connection during cognitive work speaks a language that standard HRV metrics cannot hear. Researchers and practitioners relying solely on RMSSD or LF/HF during mental tasks may be measuring the wrong dimension of the signal entirely.

Study Link: View Article

3. Concussion Cleared — But Is the Nervous System?

Delling-Brett, Jakobsmeyer, Coenen, and Reinsberger published an exploratory study in Scientific Reports examining nocturnal autonomic activity in athletes with regular versus prolonged return to sport after concussion.

Key Findings: No autonomic differences were found between groups during active recovery. But post-clearance, athletes with prolonged recovery showed significantly lower nocturnal RMSSD and fewer phasic electrodermal activity events during sleep — even after symptoms had fully resolved.

Significance: Clinical symptom clearance and autonomic recovery may be running on different timelines. Nocturnal HRV could capture a layer of incomplete recovery that symptom checklists cannot see.

Study Link: View Article

4. After a Heart Attack, Which Way Is Your HRV Heading?

Marković, Petrović, Babić, Bojić, and Milovanović published a retrospective-prospective study in Diagnostics tracking short-term HRV in 230 heart attack patients at day one and day twenty-one post-infarction.

Key Findings: Patients who died during follow-up showed lower HRV at day 21 and more pronounced declines across the three-week window. Decreased delta LF and shorter RR intervals independently predicted overall mortality in multivariable analysis.

Significance: The direction of HRV change after a heart attack — not just its level — carries independent prognostic value. Two five-minute ECG recordings, three weeks apart, may be one of the most underutilized bedside tools in post-infarct care.

Study Link: View Article

5. Can HRV Tell the ER Who Is About to Crash?

Seely, Barnaby, Hudek, Herry, Scales, Fernando, Brehaut, and Perry published a Phase One feasibility pilot in BioMed Research International, testing an HRV-based clinical decision support tool — Sepsis Advisor — in emergency department patients with suspected infection.

Key Findings: 92% of enrolled patients generated a usable HRV-based predictive model from a 30-minute ECG recording. Clinicians identified clear value in the tool for communication and early care escalation, but flagged interpretive literacy and time constraints as real barriers to adoption.

Significance: The technology works in the real emergency department environment. The next challenge is not engineering — it is clinical education and workflow integration. This pilot lays the groundwork for a genuinely life-saving tool.

Study Link: View Article

6. What Poincaré Plots Reveal That RMSSD Cannot

Milovanović, Marković, Petrović, Korugić, and Bojić published an observational study in Diagnostics examining Poincaré plot-derived HRV parameters in 269 patients referred for suspected autonomic dysfunction.

Key Findings: Poincaré plot parameters showed strong associations with long-term HRV indices and distinguished patients with abnormal parasympathetic reflex tests from those without. Associations with short-term HRV were generally weak, confirming that these parameters are capturing something conventional metrics miss.

Significance: Poincaré plot geometry is not a decorative repackaging of existing HRV data. It adds a complementary analytical layer that may improve autonomic phenotyping in clinical populations — particularly for parasympathetic reflex dysfunction.

Study Link: View Article

7. Runners Are Tracking HRV. Almost None Are Using It

Carnes and Mahoney published a survey study in the Journal of Exercise and Nutrition examining the prevalence of HRV monitoring and its application in training among 210 habitual runners.

Key Findings: 47% of runners regularly monitored HRV, with Garmin devices accounting for 71% of trackers. Male runners adopted HRV monitoring at significantly higher rates than female runners. Only 20% of HRV trackers reported adjusting their training based on the data.

Significance: The adoption problem has been solved — wearable HRV is mainstream in running communities. The utilization gap is wide open. Better in-app guidance, coaching integration, and education are the next frontier.

Study Link: View Article

8. Music as Medicine: What Happens to HRV When You Really Listen

Wang, Yu, Ma, Zhao, Wu, and Zheng published a randomized controlled trial in the Journal of Pain Research examining the effects of music intervention on pain, mood, sleep, and HRV in 79 patients with chronic pain.

Key Findings: Music therapy significantly improved depression scores and produced a measurable shift in the LF/HF ratio toward parasympathetic balance compared to the control group. Present Pain Intensity sub-scores were also significantly lower in the music group. No significant inter-group differences were found for anxiety or sleep outcomes.

Significance: Music listening is not just a pleasant distraction from pain — it is producing an objective, measurable change in autonomic balance. This is a randomized controlled trial, not an anecdote. For chronic pain management, music therapy now has a physiological evidence base to stand on.

Study Link: View Article

9. The Gut, the Brain, and the Sleep That Suffers — Differently in Girls and Boys

Kamp, Burr, Matherne, Simonds, Murphy, Heitkemper, Levy, Shulman, and van Tilburg published a study in Neurogastroenterology & Motility examining the relationships between HRV and sleep in 156 children aged 7–12 with abdominal pain-related disorders of gut-brain interaction.

Key Findings: In girls, greater parasympathetic activity was associated with longer sleep onset delay and greater sleep anxiety. In boys, lower autonomic balance was associated with greater daytime sleepiness. In both sexes, lower LF HRV was associated with sleep-disordered breathing, confirmed by post hoc analysis showing significantly lower HRV in children with disordered breathing.

Significance: The autonomic fingerprint of sleep disruption in children with functional gut pain is real — and it is not the same in girls and boys. Research designs and clinical management protocols that ignore sex differences in this population are missing a critical piece of the picture.

Study Link: View Article

Key Themes from This Week

HRV Beyond the Number: Three studies this week — biofeedback, chaos theory, and Poincaré plots — challenge the assumption that RMSSD or LF/HF is the whole story. The signal is richer than our standard metrics reveal, and the field is beginning to map dimensions we have long ignored.

Trajectory Over Snapshot: Whether it's a heart attack patient's HRV declining from day one to day twenty-one, or a concussion athlete's nocturnal RMSSD still suppressed after clinical clearance — this week's research consistently shows that where the autonomic system is heading matters more than where it sits today.

From Niche to Mainstream: Runners are tracking HRV at scale. Emergency physicians are piloting HRV-based triage tools. Chronic pain clinicians are seeing objective autonomic shifts from music therapy. HRV is no longer a research curiosity — it is entering everyday clinical and consumer life, and the gap between collection and meaningful action is the next problem to solve.

Sponsored by Optimal HRV:

This episode is sponsored by Optimal HRV. See not just where your HRV is today, but where it's been and where it's heading — with trend analysis built around your personal baseline. Whether you're a clinician, coach, researcher, or individual tracking your own recovery, Optimal HRV gives you the tools to turn daily readings into meaningful insight.

Learn more at www.optimalhrv.com.

Medical Disclaimer: This podcast is for educational purposes only. The information discussed does not constitute medical advice. Always consult a qualified healthcare professional before making changes to your health, training, or recovery protocols.

1. The Gateway of Fear: HRV, Pain, and Perception

A study in the Journal of Clinical Medicine by Venezia et al. explored the psychological architecture of pain. Researchers investigated whether our physiological "braking system" (HRV) explains why people who fear pain actually feel it more intensely.

• Key Findings: The study found that HRV significantly mediates the relationship between a person’s "Fear of Pain" and their actual "Pain Perception." Essentially, a more flexible autonomic nervous system can buffer the impact of fear on the physical experience of pain.

• Significance: This suggests that improving autonomic regulation isn't just about heart health; it’s a viable strategy for chronic pain management and desensitization.

• Study Link: View Article

2. Impulsivity and the Bottle: Alcohol Cue-Induced HRV

Published in Addictive Behaviors Reports, Taniajura and colleagues looked at "cue-reactivity"—how the body responds to the sight or smell of alcohol—and how impulsivity plays a role in drinking behavior.

• Key Findings: The research identified a specific link between alcohol-cue-induced HRV changes and subsequent drinking, particularly in individuals with high impulsivity.

• Significance: HRV may serve as a real-time "relapse warning system," identifying moments when an individual’s self-regulation is compromised by environmental triggers.

• Study Link: View Article

3. Cognitive Performance in the Heat: 150 Minutes of Stress

As global temperatures rise, understanding heat-induced cognitive fatigue is critical. Zhu et al. published a study in Energy and Buildings focusing on human attentional performance during sustained heat exposure.

• Key Findings: Using HRV indices, researchers predicted shifts in human attention and performance after 150 minutes of heat exposure.

• Significance: This provides a blueprint for "smart buildings" and occupational safety protocols that use wearable HRV data to prevent heat-related errors in industrial settings.

• Study Link: View Article

4. Protecting the Frontline: HRV in Agricultural Workers

In a parallel vein to the study above, Lung et al. (published in Nature) utilized lightweight personal sensors to track agricultural workers in the field.

• Key Findings: The study validated an "innovative method" for evaluating the immediate impact of environmental heat on the autonomic nervous system of outdoor laborers.

• Significance: This moves HRV research out of the lab and into the "real world," proving that mobile sensors can effectively monitor the health of vulnerable populations in extreme climates.

• Study Link: View Article

5. Inside the Heart: HRV in the Operating Room

A study in Frontiers in Physiology by Skoczyński et al. took HRV into the most acute setting possible: cardiac surgery. They used short-term HRV metrics to assess the heart's parasympathetic response to rapid atrial pacing.

• Key Findings: Short-term HRV metrics proved effective for intraoperative assessment of the cardiac parasympathetic response.

• Significance: This demonstrates that HRV isn't just for long-term wellness tracking; it can be used for "micro-assessments" during complex medical procedures to guide surgical decisions.

• Study Link: View Article

6. The Nightly Grind: Sleep Bruxism and Sleep Apnea

Przegrałek et al. investigated the "silent modifiers" of autonomic health in a study published in Sleep. They looked at how sleep bruxism (teeth grinding) affects patients already suffering from obstructive sleep apnea (OSA).

• Key Findings: Bruxism acts as a potential modifier of autonomic function, further destabilizing HRV in patients with OSA.

• Significance: For clinicians treating sleep disorders, this highlights the need to look beyond oxygen levels and consider how muscular tension and grinding during sleep create a "double hit" to the autonomic nervous system.

• Study Link: View Article

7. Vertigo and the Vagus: The Catestatin Connection

A fascinating observational study in the Journal of Family Medicine and Primary Care examined the relationship between vertigo, baroreceptor sensitivity, and a protein called catestatin.

• Key Findings: Patients with vertigo showed significant associations between suppressed HRV and altered serum catestatin levels.

• Significance: This adds a biochemical layer to our understanding of balance disorders, suggesting that vertigo is deeply intertwined with systemic autonomic dysregulation.

• Study Link: View Article

8. Precision Under Fire: Psychological Skills for Police

In Frontiers in Psychology, Liang et al. conducted a randomized controlled trial on a novel training program for police pistol use across high-stress operational scenarios.

• Key Findings: Integrated psychological skill training improved performance and stabilized autonomic responses (HRV) during tactical shooting.

• Significance: This confirms that "tactical breathing" and psychological conditioning are not just "soft skills"—they are physiological requirements for maintaining accuracy and decision-making under life-or-death pressure.

• Study Link: View Article

9. The Digital Athlete: Acute Effects of Esports on HRV

A systematic review and meta-analysis in Frontiers in Physiology by Lyu et al. addressed the growing world of professional gaming.

• Key Findings: Esports induce significant acute changes in HRV, reflecting high levels of mental stress and sympathetic activation, similar to those observed in traditional high-pressure sports.

• Significance: This legitimizes the need for "autonomic recovery" protocols for professional gamers, who may be suffering from chronic sympathetic dominance despite the sedentary nature of their "sport."

• Study Link: View Article

10. Lighting the Way: Photobiomodulation and Recovery

Finally, Pereira et al. published a trial in the Journal of Biophotonics examining how light therapy (Photobiomodulation) affects HRV in physically active individuals.

• Key Findings: Acute light therapy application was shown to modulate HRV, facilitating the transition from a stressed to a recovery state.

• Significance: This reinforces the "passive regulation" trend, suggesting that targeted light therapy could be a powerful tool for athletes to "jumpstart" their parasympathetic recovery after intense training.

• Study Link: View Article

Key Themes from This Week

• The Environment as a Stressor: Multiple studies this week highlight how heat—both in the lab and in the field—is a primary antagonist to autonomic health and cognitive performance.

• HRV as a "Bridge": From pain to alcohol cravings, HRV is being used as the missing link between a psychological "trigger" and a physical "action."

• Cross-Domain Applications: Whether it’s a police officer on the range, a gamer in a tournament, or a surgeon in the OR, HRV is becoming the universal language of performance and safety.

Sponsored by Optimal HRV:

This episode is sponsored by Optimal HRV. Get the most out of your data with resonance-frequency breathing and curated session views.

Learn more at optimalhrv.com

Medical Disclaimer: This podcast is for educational purposes only. Always consult a healthcare professional before changing your health or recovery protocols.

1. Heart Rate Fragmentation: A New Window into Allostatic Load

A study published in Applied Psychophysiology and Biofeedback by Jennifer F. Chan, Judith Andersen, and colleagues introduced a novel non-linear HRV metric called Heart Rate Fragmentation (HRF). Unlike traditional metrics that look at the magnitude of variability, HRF tracks the frequency of "directional changes" in heart rate (accelerations vs. decelerations), which can signal a breakdown in autonomic control.

• Key Findings: Analyzing 156 healthy adults, researchers found that while traditional HRV indices didn't always distinguish between healthy and "probable mental health" (pMH) groups, HRF reactivity was significantly higher in healthy individuals ($p < 0.001$).

• Significance: HRF may serve as a more sensitive biomarker for allostatic load (the "wear and tear" on the body), capturing subtle autonomic dysregulation that standard time-domain metrics might miss.

• Study link: https://link.springer.com/article/10.1007/s10484-025-09721-1

2. The Power of Brief Mindfulness Meditation

A systematic review published in Applied Psychophysiology and Biofeedback investigated whether "Brief Mindfulness Meditation" (BMM) is sufficient to induce measurable changes in cardiac autonomic tone. The research team synthesized data from across four major databases to clarify the "dose-response" relationship between mindfulness and HRV.

• Key Findings: The review highlights that even single-session or short-term mindfulness interventions can significantly influence HRV, particularly increasing parasympathetic markers.

• Significance: This provides robust evidence for the clinical use of "micro-interventions," suggesting that patients and athletes don't necessarily need years of practice to begin re-regulating their autonomic "baseline."

• Study link: https://link.springer.com/article/10.1007/s10484-025-09724-y

3. Setting Digital Psychiatry in Motion

A perspective published in NPP—Digital Psychiatry and Neuroscience (Nature Portfolio) by Axel Constant, Emre Koksal, and Lena Palaniyappan argues for a shift toward Dynamic Digital Markers (DDMs). The authors critique "static" entropy measures, which summarize data over long periods, potentially losing the "motion" of psychiatric symptoms.

• The Proposal: By using smartphones and wearables to track moment-to-moment temporal dependencies, clinicians can capture the dynamic regulatory mechanisms of psychopathology.

• Significance: This approach moves HRV and digital phenotyping from a diagnostic "label" to a "weather map" that can predict shifting, unstable mental states in real time.

• Study link: https://www.nature.com/articles/s44277-026-00059-y

4. Photobiomodulation: Light Therapy for the Vagus Nerve

A randomized controlled trial published in Scientific Reports (available via PMC) explored an innovative intervention: Photobiomodulation (PBM). Researchers applied light therapy to the infra-auricular region (targeting the vagus nerve) in physically active individuals to see if it could modulate autonomic recovery following exercise.

• Key Findings: The study is the first to demonstrate that non-invasive light acting on the vagal pathway can influence HRV parameters. It suggests that PBM may offer a "passive" way to enhance vagal control over the heart.

• Significance: This opens a new frontier for "bio-hacking" and clinical recovery, providing a potential technological shortcut to enhance parasympathetic tone without requiring active participation, such as breathing or meditation.

• Study link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12976981/

5. Biofeedback for Music Performance Anxiety

A systematic review in Applied Psychophysiology and Biofeedback examined the use of HRV and neurofeedback to manage Music Performance Anxiety (MPA). Musicians often face extreme sympathetic arousal that can degrade fine motor skills and performance quality.

• Key Findings: Structured biofeedback training programs significantly enhanced musicians' capacity for self-regulation. Successful interventions were associated with improved HRV and higher scores on the Kenny Music Performance Anxiety Inventory (K-MPAI) and the Music Performance Quality Scale (MPQ).

• Significance: The study emphasizes that for high-stakes performers, HRV biofeedback isn't just about "calming down"—it’s about finding the optimal "resonance frequency" to maintain technical precision under pressure.

• Study link: https://link.springer.com/article/10.1007/s10484-025-09722-0

Key Themes from This Week

• Moving Beyond the Average: New metrics like Heart Rate Fragmentation and Dynamic Digital Markers show that how heart rate changes over time is as important as the magnitude of those changes.

• Passive vs. Active Regulation: While mindfulness remains the gold standard for active regulation, emerging technologies such as photobiomodulation offer passive ways to support the vagal brake.

• Precision Performance: Biofeedback continues to prove its worth in high-pressure environments, from the stage to the training ground, by stabilizing the "autonomic basement."

Sponsored by Optimal HRV

This episode is sponsored by Optimal HRV. Optimal HRV provides research-based measurement and resonance-frequency breathing guidance. Recent updates include independent widget toggles for the heart rate chart, OZ gauge, pacer, and suggestions, allowing users to curate their session view. The team is also implementing font scaling fixes and preparing for upcoming mindfulness audio integration.

Learn more: https://optimalhrv.com

Medical Disclaimer

This podcast is for educational and informational purposes only and does not constitute medical advice. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before applying any strategies discussed.

1. Nutritional Modulation of the Vagal Brake

A systematic review and meta-analysis published in the World Journal of Clinical Pediatrics investigated how Omega-3 fatty acid supplementation influences cardiac autonomic regulation. Researchers Hoda Atef Abdelsattar Ibrahim, Kamal Gouda Kamal, Mohamed Khaled Ali Mohamed Ali Zid, Albraa Ashraf Hamad, Ayesha Kuraishi, and Marwa Taha analyzed data from multiple randomized controlled trials. The results showed that Omega-3 supplementation was associated with a significant increase in time-domain HRV indices, including RMSSD and SDNN. This suggests that essential fatty acids may enhance the sinoatrial node's sensitivity to parasympathetic input, thereby stabilizing the heart's electrical threshold.

Study link: https://www.wjgnet.com/2219-2808/full/v15/i1/116331.htm

2. Social Anxiety and Autonomic Expression in VR A study published in the Journal of Medical Internet Research explored the automated inference of social anxiety using behavioral data captured in virtual reality. Authors Gayoung Son and Marius Rubo used eye trackers and microphones to monitor 128 participants during a 30-minute social interaction. Higher levels of social anxiety were significantly linked to:

• Reduced high-frequency HRV (HF-HRV)

• Reduced gaze toward the partner’s eyes while speaking

• Quieter speech volume: The study found a strong correlation (r = 0.94) between these behaviors and broader psychopathology, suggesting that our "autonomic basement" displays consistent safety behaviors across digital and physical environments.

Study link: https://www.jmir.org/2026/1/e79147

3. HRV as a Sentinel for Neonatal Morbidity

A study published in Pediatric Research by Karen D. Fairchild examined the predictive value of depressed HRV in the neonatal intensive care unit. The study utilized advanced signal processing to monitor cardioregulatory patterns in both preterm and term infants. Lower HRV indices were robustly linked to:

• Intraventricular hemorrhage (IVH)

• Necrotizing enterocolitis (NEC)

• Chronic lung disease: While depressed HRV serves as a "canary in the coal mine," the author emphasizes that predictive power varies by gestational age and postnatal development, requiring context-aware clinical interpretation.

Study link: https://www.nature.com/articles/s41390-026-04897-6

4. Ocular Hemodynamics and Systemic Autonomic Health A study published in PLOS ONE investigated the relationship between heart rate variability and retinal vein occlusion (RVO) in glaucoma patients. Researchers Ji Hye Lee and Young-Hoon Park compared 29 patients who developed RVO with 34 controls. The RVO group showed significantly lower autonomic and vascular markers:

• SDNN was 22.12 \pm 8.27 compared to 36.71 \pm 24.74 in controls (p = 0.002)

• RMSSD was 16.34 \pm 9.55 compared to 29.87 \pm 31.58 in controls (p = 0.022)

• Significantly lower Choroidal Vascularity Index (CVI): This suggests that low HRV may be a vulnerability marker for ocular vascular complications, reflecting a systemic lack of hemodynamic stability.

Study link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0324110

Key Themes from This Week

Across these studies, several important themes emerge:

• A nutritional substrate (Omega-3s) stabilizes the cardiac circuitry.

• Digital environments can mirror naturalistic autonomic safety behaviors.

• Depressed HRV provides a predictive window for systemic illness in critical care.

• Systemic hemodynamic instability is a risk factor for localized organ failure.

  Heart rate variability continues to demonstrate its value not as a single number, but as a dynamic reflection of adaptability across the entire lifespan.

Sponsored by Optimal HRV

This episode is sponsored by Optimal HRV. Optimal HRV provides research-based measurement and resonance-frequency breathing guidance. Recent updates include independent widget toggles for the heart rate chart, OZ gauge, pacer, and suggestions, allowing users to curate their session view. The team is also implementing font scaling fixes and preparing for upcoming mindfulness audio integration. Learn more: https://optimalhrv.com

Medical Disclaimer

This podcast is for educational and informational purposes only and does not constitute medical advice. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before applying any strategies discussed.

These papers span wearable digital biomarkers, sleep medicine, machine learning and mental health, critical care pharmacology, virtual environments, stroke recovery, and intermittent hypoxia.

Across all seven studies, one theme emerges clearly:

HRV reflects the structure of physiological adaptability.

The nervous system is constantly adjusting to behavioral habits, environmental stressors, emotional meaning, and disease processes. HRV captures those adjustments as patterns of variability, complexity, and stability.

1. HRV Stability as a Digital Biomarker of Behavior

A large study published in the American Journal of Physiology – Heart and Circulatory Physiology examined the stability of HRV measurements across multiple nights of wearable recordings.

Researchers analyzed nearly 2 million nocturnal HRV measurements from over 21,000 individuals.

Instead of focusing on single HRV readings, the study measured the coefficient of variation of HRV (HRV-CV) — essentially how much HRV fluctuates from night to night.

The results revealed that five nights of data are required to reliably estimate a person’s baseline HRV stability.

Higher HRV variability was associated with:

• Greater alcohol consumption

• Lower physical activity

• Shorter sleep duration

• Irregular sleep timing

This suggests that autonomic stability may function as a digital biomarker of behavioral consistency.

Study link: https://journals.physiology.org/doi/10.1152/ajpheart.00738.2025

2. Sleep Interventions and the “Autonomic Lag”

A systematic review and meta-analysis published in the European Heart Journal Open examined how behavioral sleep interventions influence cardiovascular physiology.

Researchers evaluated randomized controlled trials studying treatments such as Cognitive Behavioral Therapy for Insomnia (CBT-I).

Sleep interventions significantly improved:

• Systolic blood pressure

• Diastolic blood pressure

However, HRV parameters did not significantly change.

The researchers propose what may be described as an “autonomic lag.”

While sleep improvements quickly influence vascular physiology, deeper remodeling of the autonomic nervous system may take months of consistent behavioral change.

Study link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12915584/

3. Machine Learning and HRV-Based Depression Detection

A study published in Frontiers in Digital Health explored whether HRV signals can be used to classify depression using machine learning algorithms.

Researchers addressed a common challenge in biomedical AI: imbalanced datasets, where healthy participants greatly outnumber patients.

Using a hybrid method called SMOTE-ENN, the team balanced the dataset and trained several models, including:

• Support Vector Machines

• Random Forest

• Neural Networks

• K-Nearest Neighbors

The optimized models achieved over 91% classification accuracy.

The most influential physiological feature was SDNN, representing total autonomic variability.

This reinforces the idea that depression may involve reduced physiological adaptability within the autonomic nervous system.

Study link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12935896/

4. Medication Effects on HRV in Critical Care

In a review published in Critical Care Explorations, researchers investigated how medications commonly used in intensive care settings influence HRV.

The review analyzed twenty-eight major HRV studies involving critically ill patients.

Surprisingly, none of them rigorously accounted for medication exposure.

Yet many ICU medications directly affect autonomic activity:

• Beta-blockers often increase HRV

• Vasopressors can dramatically suppress HRV

• Sedatives such as propofol alter autonomic tone

• SSRIs may decrease HRV

This means HRV signals recorded in ICU environments may reflect both physiological distress and pharmacological effects.

Future predictive models will likely need medication correction factors to interpret HRV accurately.

Studylink:https://journals.lww.com/ccejournal/fulltext/2026/03000/medication_effects_on_heart_rate_variability_in.3.aspx

5. Narrative, Meaning, and Physiological Engagement

An interdisciplinary study published in npj Heritage Science examined how storytelling shapes physiological responses inside virtual environments.

Participants explored a digital reconstruction of an industrial heritage site while researchers recorded eye-tracking data and heart rate variability.

Without narrative guidance, participants showed scattered attention patterns and inconsistent physiological responses.

When narrative context was added:

• Visual attention became synchronized

• HRV fluctuations aligned with narrative events

The findings suggest that meaning itself can organize physiological engagement.

The nervous system responds not only to physical stimuli, but also to interpretation.

Study link: https://www.nature.com/articles/s40494-026-02352-7

6. HRV Complexity and Stroke Complications

A study published in BMC Neurology investigated whether HRV could predict complications following mechanical thrombectomy in stroke patients.

Researchers analyzed HRV data from 254 patients.

Instead of traditional HRV measures, they examined nonlinear complexity metrics, including Composite Multiscale Entropy (CMSE).

Patients who later developed hemorrhagic transformation showed significantly lower HRV complexity.

Reduced complexity may reflect sympathetic overactivation and impaired autonomic regulation following severe brain injury.

HRV complexity metrics could eventually become part of risk monitoring systems in stroke units.

Study link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12911255/

7. Intermittent Hypoxia and Autonomic Risk Patterns

A study published in Hypertension Research explored how different patterns of oxygen deprivation affect cardiovascular and neurological outcomes.

Researchers exposed animals to intermittent hypoxia with different temporal patterns.

Even though the total oxygen deficit was similar, the outcomes differed dramatically:

Rapid five-second hypoxia cycles produced:

• Sustained hypertension

• Severe autonomic dysfunction

Longer ten-second hypoxia cycles produced:

• Neuroinflammation

• Memory impairment

These findings highlight a crucial insight:

The timing of physiological stress can determine which organ systems are affected.

Study link: https://www.nature.com/articles/s41440-026-02588-7

Key Themes from This Week

Across these studies, several important themes emerge:

• Autonomic stability reflects behavioral patterns
• Sleep improvements may precede HRV changes
• Machine learning may unlock HRV biomarkers for mental health
• Medication exposure can distort HRV interpretation
• Meaning and narrative can shape physiological engagement
• Reduced HRV complexity may signal neurological risk
• The structure of stress exposure influences disease outcomes

Heart rate variability continues to demonstrate its value not as a single number, but as a dynamic reflection of adaptability across biological systems.

Sponsored by Optimal HRV

This episode is sponsored by Optimal HRV.

Optimal HRV provides research-based HRV measurement, resonance-frequency breathing guidance, and long-term autonomic tracking designed for clinicians, therapists, and performance specialists.

Learn more:
https://optimalhrv.com

Medical Disclaimer

This podcast is for educational and informational purposes only and does not constitute medical advice. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before applying any strategies discussed.

From perceived stress in healthy adults to social brain plasticity, from acute cold exposure to wearable-driven dementia detection, this episode emphasizes HRV as a real-time window into autonomic adaptability and system resilience.

HRV is increasingly understood as a measure of regulatory range — the nervous system’s capacity to flex, adapt, and recalibrate. Across the studies reviewed this week, HRV emerges not merely as a marker of stress, but as a functional reflection of how the brain and body coordinate in response to internal and external demands.

Studies Reviewed in This Episode

1. Perceived Stress and Autonomic Regulation in Healthy Adults

Study: The Relationship Between Perceived Stress Scale and Heart Rate Variability in Healthy Adults

Authors: Alper Perçin, Ramazan Cihad Yılmaz, Dilan Demirtaş Karaoba, and Büsra Candiri

Link: https://www.researchgate.net/publication/401048214_The_Relationship_Between_Perceived_Stress_Scale_and_Heart_Rate_Variability_in_Healthy_Adults

Key Insight: Higher perceived stress scores were significantly associated with lower vagally mediated HRV indices, including RMSSD and high-frequency power. Even in healthy adults without psychiatric diagnoses, subjective stress perception meaningfully aligned with reduced parasympathetic flexibility.

Clinical Relevance: HRV and psychological stress scales measure overlapping but distinct domains. When both subjective stress and HRV suppression are present, vulnerability may increase. Divergence between the two may provide additional diagnostic insight into resilience or under-recognized physiological load.

2. Neural Mechanisms of Social Homeostasis and Dynamic Range Plasticity

Study: Neural Mechanisms of Social Homeostasis: Dynamic Range Plasticity

Authors: Jianna Cressy, Caroline Jia, Jonathan Salk, and Kay M. Tye

Link: https://www.jneurosci.org/content/46/8/e0224252025

Key Insight: The study demonstrates that neural systems responsible for social regulation exhibit dynamic plasticity, adjusting their functional range in response to environmental demands. This adaptive range mirrors principles found in neurovisceral integration models, where flexibility in central networks is reflected in peripheral autonomic flexibility.

Clinical Relevance: HRV may serve as a peripheral marker of central regulatory capacity. Interventions that enhance autonomic flexibility — including biofeedback and resonance breathing — may indirectly support neural adaptability involved in emotional and social regulation.

3. Acute Cold Exposure and Cognitive Performance

Study: The Immediate Effect of Cold Spinal Spray and Cold Spinal Bath on Cognition Among Young Adults: A Three-Armed Randomized Controlled Trial

Authors: Avishee Sinha and Sujatha KJ

Link: https://www.cureus.com/articles/386403-the-immediate-effect-of-cold-spinal-spray-and-cold-spinal-bath-on-cognition-among-young-adults-a-three-armed-randomized-controlled-trial#!/

Key Insight: Cold spinal spray and cold spinal bath produced short-term changes in cognitive performance among young adults. The likely mechanism involves acute sympathetic activation and catecholamine release, temporarily enhancing alertness and vigilance.

Clinical Relevance: Cold exposure may increase cognitive arousal but may simultaneously reduce short-term HRV due to sympathetic activation. This distinction between heightened alertness and autonomic flexibility is critical when designing performance or recovery protocols.

4. AI and Wearables for Early Detection of Cognitive Impairment

Study: AI and Wearables for Early Detection of Cognitive Impairment and Dementia: Systematic Review

Authors: Ander Cejudo, Markel Arrojo, Cristina Martín, and Aitor Almeida

Link: https://www.jmir.org/2026/1/e86262

Key Insight: Across multiple reviewed studies, wearable physiological signals — including HRV-derived metrics — improved machine-learning classification accuracy for distinguishing cognitively healthy individuals from those with early impairment.

Clinical Relevance: HRV-based wearable monitoring may become a scalable, non-invasive screening tool for early cognitive decline. Autonomic dysregulation appears to precede overt cognitive symptoms, offering a potential window for earlier intervention.

Integrated Takeaways

• Perceived stress and HRV are connected but not interchangeable.
• Autonomic flexibility mirrors central neural adaptability.
• Sympathetic arousal can enhance performance while reducing short-term HRV.
• Wearable HRV integrated with artificial intelligence may help detect early neurodegenerative risk.

Together, these studies reinforce HRV as a dynamic marker of regulatory capacity — spanning psychology, neuroscience, performance physiology, and cognitive health.

Sponsor

This episode is brought to you by Optimal HRV.
Explore professional-grade autonomic analytics, trauma-informed biofeedback tools, and longitudinal HRV tracking at OptimalHRV.com.

If you found this episode valuable, please subscribe and share it with a colleague. We’ll continue exploring the evolving science of autonomic regulation next week.

In this week’s episode, host Matt Bennett moves beyond environmental stressors to explore the biological architecture that governs our autonomic responses. From the inflammatory milieu of coronary arteries to the 24-hour coordination of the circadian axis, we analyze how Heart Rate Variability (HRV) serves as a blueprint for physiological integrity and a non-invasive window into the developing brain.

Thematic Overview: HRV as a Blueprint

While HRV is often used as a reactive "stress score," the latest research indicates it functions as a predictor of structural stability. This episode highlights HRV as a transdiagnostic marker of autonomic flexibility, shifting the clinical focus from mere observation to the identification of causal pathways of chronic disease and neurodevelopmental risk.

Studies Reviewed in This Episode

1. Coronary Plaque Vulnerability and AI-Driven Imaging

• Study: Heart rate variability, unstable coronary plaques, and cardiovascular outcomes

• Authors: Yue Yu, Weifeng Guo, Ziwei Shen, Han Chen, Changyi Zhou, Cheng Yan, Yanli Song, Chenguang Li, Mengsu Zeng, Li Shen, Dijia Wu, Jiasheng Yin, and Junbo Ge

• Key Finding: Lower HRV (specifically SDNN) is independently associated with higher Fat Attenuation Index (FAI) values—a high-fidelity biomarker for inflammation in the perivascular adipose tissue surrounding the heart. Each 1-SD decrease in SDNN was associated with a 2.05-fold increase in the risk of major adverse cardiovascular events.

2. Schizophrenia and Cognitive Endophenotypes

• Study:(https://www.cureus.com/articles/447595-heart-rate-variability-and-cognitive-function-as-potential-endophenotypes-in-schizophrenia-a-cross-sectional-observational-study-using-first-degree-relatives#!/)

• Authors: Priyadarsini Samanta, Barsha B. Parida, Jigyansa I. Pattnaik, Rama Chandra Das, Rashmi Kumari, Vedaant Parekh, Jayanti Mishra, Jyotiranjan Sahoo, and Laxman Kumar Senapati

• Key Finding: Patients with schizophrenia exhibit a significantly higher LF/HF ratio compared to healthy relatives (1.57 vs. 0.79), indicating chronic sympathovagal imbalance. This autonomic profile showed a strong positive correlation with cognitive performance on the Wechsler Abbreviated Scale of Intelligence.

3. Exercise Physiology and the Fractal Heart ($DFA \alpha 1$)

• Study: Agreement between heart rate variability-derived and lactate/ventilatory thresholds during a 4-min stepwise incremental cycling test in male adults

• Authors: Anton Olieslagers, Yoram Müller-Jabusch, Margot Vancoillie, Emma Delen, and Toon de Beukelaar

• Key Finding: The non-linear metric DFA \alpha 1 at a value of 0.50 (HRVT2) is a highly accurate surrogate for the anaerobic threshold. However, the lower aerobic threshold (HRVT1 at 0.75) demonstrated poor agreement with gold-standard metabolic markers, suggesting it is not yet reliable for setting low-intensity zones.

4. Neonatal Maturation and Neurodevelopmental Risk

• Study:(https://onlinelibrary.wiley.com/doi/10.1111/apa.70462?af=R)

• Authors: Léa Bonneau, Cyril Flamant, Maxime Esvan, Jean Michel Roué, Géraldine Favrais, Géraldine Gascoin, Sandie Cabon, Fabienne Porée, Guy Carrault, and Patrick Pladys

• Key Finding: Using machine learning to estimate "Functional Maturation Age," the team found that infants with complications such as bronchopulmonary dysplasia or patent ductus arteriosus experienced significant delays in maturation. Each week of HRV maturation delay doubled the odds of having altered social communication skills at 2 years of age.

5. The Circadian Axis of Brain-Body Organization

• Study: Control vs. salience: a new axis of circadian brain-body organization

• Authors: Olivier Demers, Sanaz Ghaffari, Chen Li, and Russell Butler

• Key Finding: Circadian health is organized along a Control-Salience axis, with individuals with locomotor-dominant rhythms showing stronger cognitive control network connectivity, while those with autonomic-dominant rhythms showing tighter heart rate-activity coupling and stronger salience network connectivity.

6. Meditation as Autonomic Gym Training

• Study:(https://link.springer.com/chapter/10.1007/978-981-96-8309-3_39)

• Authors: Vivek Ranjan, Raghuwansh Singh, Anindita Ganguly, and Suman Halder

• Key Finding: Advanced machine learning algorithms (Random Forest and SVM) successfully distinguished meditative from pre-meditative states with up to 99.5% accuracy. The research demonstrates that meditation increases the textural complexity and flexibility of the heart rhythm, effectively "training" the autonomic nervous system.

Practical Takeaways

• For Clinicians: HRV maturation analysis (Delta HRV) provides a non-invasive window into neonatal brain health, while time-domain HRV can signal vulnerable coronary plaque phenotypes early.

• For Individuals: Protecting your nocturnal HRV peak through consistent circadian rhythms and engaging in "autonomic training" like Yoga Nidra or Vipassana are proven strategies to rewire your baseline resilience.

Sponsors: This episode is brought to you by Optimal HRV. Explore professional-grade autonomic analytics for your coaching or clinical practice at OptimalHRV.com.

Upcoming Events: We hope to see you at the BFE 2026 meeting! Connect with the world’s leading autonomic researchers and biofeedback practitioners this spring.

Across all five papers, one theme emerges clearly:

HRV reflects adaptability.

Whether we are celebrating a goal, training the brain, fasting, recovering from illness, or navigating adolescence, autonomic flexibility shapes outcomes.

⚽ Football Fever: HRV During Competitive Match Viewing

A new study published in Scientific Reports (Nature Portfolio) investigates real-time cardiovascular and autonomic responses during high-stakes football matches.

Researchers monitored spectators’ heart rates and HRV during key match events—goals, penalties, near misses, and final outcomes. Moments of uncertainty and threat to the favored team produced:

• Significant reductions in vagally mediated HRV

• Rapid increases in heart rate

• Sustained sympathetic activation in some individuals

Recovery patterns differed based on match outcomes, with prolonged vagal withdrawal observed following unexpected losses.

This research provides mechanistic insight into why major sporting events have been associated with spikes in cardiovascular incidents at the population level.

Study link:
https://www.nature.com/articles/s41598-026-36182-1

Neurofeedback and Autonomic Regulation

Published through Scientific Research Publishing, this study examined whether structured neurofeedback training influences heart rate variability and cognitive performance.

Participants completed multiple neurofeedback sessions targeting EEG regulation associated with attention and emotional control. Findings included:

• Increases in parasympathetic HRV markers

• Improved cognitive task performance

• Reductions in anxiety-related symptoms

The results support a bidirectional neurocardiac integration model — suggesting that improving cortical regulation may enhance vagal tone.

For clinicians, this raises compelling questions about combining neurofeedback and HRV biofeedback for synergistic regulatory effects.

Study link:
https://www.scirp.org/journal/paperinformation?paperid=149580

⏳ Fasting, Cardiometabolic Health, and Autonomic Balance

In a paper published in Arteriosclerosis, Thrombosis, and Vascular Biology (American Heart Association), researchers examined the cardiovascular effects of structured fasting interventions.

Key findings included:

• Improvements in triglyceride levels

• Enhanced insulin sensitivity

• Variable autonomic responses depending on metabolic status

Early fasting phases were associated with increased sympathetic activity in some participants, while longer-term adaptation appeared to stabilize or improve HRV in metabolically resilient individuals.

This highlights an important clinical principle:

Fasting is a physiological stressor. Whether it becomes adaptive depends on individual autonomic resilience.

Study link:
https://www.ahajournals.org/doi/10.1161/ATVBAHA.125.323355

HRV as a Predictor of Organ Dysfunction

Published in the Journal of Clinical Monitoring and Computing, this study explored heart rate variability as a biomarker of organ dysfunction in critically ill patients.

Researchers found that:

• Reduced HRV was associated with worsening organ failure scores

• Decreased complexity and vagal markers often preceded overt clinical deterioration

This reinforces a core systems principle:

Health is characterized by variability.
Rigidity signals loss of adaptive capacity.

HRV may function as an early warning indicator in critical care environments.

Study link:
https://link.springer.com/article/10.1007/s10877-026-01417-z

‍ Adolescence and Autonomic Development

A new study in Physiological Reports examined autonomic maturation during adolescence and its implications for long-term cardiovascular health.

Findings suggest that:

• Adolescence involves dynamic remodeling of sympathetic and parasympathetic balance

• HRV trajectories during this developmental window may influence future cardiovascular risk

• Early-life stress and lifestyle factors may shape long-term autonomic resilience

Given that many mental health disorders emerge during adolescence, supporting vagal regulation during this stage may have lifelong implications.

Study link:
https://physoc.onlinelibrary.wiley.com/doi/10.14814/phy2.70769

Key Themes from This Week

• Emotional stress is embodied stress

• Brain training influences cardiac regulation

• Metabolic stress must be individualized

• Loss of variability predicts systemic decline

• Autonomic patterns established in adolescence may shape decades of health

Heart rate variability continues to demonstrate its value not as a single number, but as a dynamic reflection of adaptability across contexts.

Sponsored by Optimal HRV

This episode is sponsored by Optimal HRV.

Optimal HRV provides trauma-informed, research-based HRV assessment and biofeedback tools designed specifically for clinicians and healthcare professionals. The platform supports tracking of the nervous system, resilience training, and structured biofeedback in clinical and performance settings.

Learn more at:
https://optimalhrv.com

Medical Disclaimer

This podcast is for educational and informational purposes only and does not constitute medical advice. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before applying any strategies discussed.

This episode emphasizes HRV as a marker of felt safety, autonomic integration, and physiological sensing, highlighting how vagal activity reflects not only brain-mediated regulation but also incoming sensory information from the body. Implications are discussed for clinicians, researchers, and individuals seeking a more nuanced and compassionate understanding of nervous system function.

Medical Disclaimer

This podcast is for educational and informational purposes only and does not constitute medical advice. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before making changes to medical care, mental health treatment, or lifestyle practices.

STUDIES DISCUSSED IN THIS EPISODE

Felt Safety and Body-Oriented Trauma Intervention

Full Title:
From Somatic Experiencing to felt safety: Assessing the effects of a body-oriented intervention in adults with various degrees of child maltreatment

Authors:
Jörgen Lehmivaara
Billy Jansson
Jens Bernhardsson
Marylène Cloitre
Monique C. Pfaltz

Journal:
European Journal of Psychotraumatology

Publication Year:
2026

Key Points:
• A brief Somatic Experiencing–based intervention significantly increased psychological safety
• Participants showed improvements in affect and social connectedness
• Heart rate decreased, and HRV increased during the intervention
• Reductions in disrupted body boundaries and increased interoceptive awareness were observed
• Findings support felt safety as an embodied, physiologically measurable state

Article Link:
https://doi.org/10.1080/20008066.2026.2613544

Autonomic Integration and the Triangle Therapy Hypothesis

Full Title:
Integrating autonomic and affective pathways in borderline personality disorder: The triangle therapy hypothesis

Author:
Daniel Juraszek

Journal:
Frontiers in Psychology

Publication Year:
2026

Key Points:
• Proposes a somatic pre-phase intervention targeting autonomic regulation
• Centers on exposure to silence, sound, and isolation as ancestral affective conditions
• Frames BPD as a disorder of autonomic-affective integration rather than cognition alone
• Suggests HRV as a physiological marker of treatment readiness and integration
• Emphasizes bottom-up tolerance before top-down therapeutic work

Article Link:
https://www.frontiersin.org/articles/10.3389/fpsyg.2026.1686068/full

Sleep-Time HRV and Migraine Prediction

Full Title:
Heart rate variability as a predictor of migraine: Sleep-time data analysis of pre-migraine nights

Authors:
Rūta Jankevičiūtė
Viroslava Kapustynska
Vytautas Abromavičius

Journal:
Technology and Health Care

Publication Year:
2026

Key Points:
• Sleep-time HRV patterns differed on nights preceding migraine attacks
• Significant inter-individual variability was observed
• Machine-learning models showed promise for personalized prediction
• HRV appears most useful when analyzed longitudinally within individuals
• Highlights sleep as a low-noise window for autonomic assessment

Article Link:
https://doi.org/10.1177/09287329251412968

Long-Duration HRV in Severe Heart Failure

Full Title:
Physiological characterisation of severe heart failure using long-duration ambulatory ECG: A retrospective exploratory analysis

Authors:
Junaid Aamir Khan
Usman Ali
Md Tanzim Ahsan
Ratan Chandra Roy
Opeyemi S. Alamu
Francesco Alessi Longa

Journal:
Cureus

Publication Year:
2026

Key Points:
• Severe heart failure patients showed globally reduced HRV
• Substantial within-subject variability was observed across recording periods
• HRV and heart rate did not always move together
• Long-duration recordings captured dynamics missed by short assessments
• Supports continuous monitoring for detecting instability and decompensation

Article Link:
https://www.cureus.com/articles/456345

Vagal Sensory Receptors and Blood Volume Regulation

Full Title:
Vagal blood volume receptors compensate for haemorrhage and posture change

Authors:
Zhikai Liu
Shan Lu
Isabela A. Haskell
Michael S. Schappe
Maša Josipović
Soohong Min
AbdulRasheed A. Alabi
Jingyi Chi
Minseon Kim
Stephen D. Liberles

Journal:
Nature

Publication Year:
2026

Key Points:
• Identified vagal sensory neurons expressing PIEZO2
• These neurons encode central blood volume, not just pressure
• Essential for compensation during posture change and blood loss
• Loss of these receptors impaired autonomic stability
• Reframes vagal tone as a sensory-regulatory loop

Article Link:
https://www.nature.com/articles/s41586-025-10010-4

Sponsor

This episode is sponsored by Optimal HRV.

Optimal HRV provides trauma-informed, research-based heart rate variability biofeedback tools for clinicians, researchers, and individuals. The platform integrates HRV assessment, guided breathing, biofeedback training, and professional education to support nervous system regulation and resilience.

Learn more at:
https://optimalhrv.com

Episode Title:
HRV Across Cardiovascular Disease, Stress, Cognition, Development, and Social Connection

Episode Summary:
In Episode 23 of the Heart Rate Variability Podcast, we take an in-depth look at six recent peer-reviewed studies that collectively illustrate how heart rate variability (HRV) is being used across medicine, neuroscience, psychology, and emerging technologies. From cardiovascular disease prognosis to chronic stress burden, from Alzheimer’s-related fall risk to virtual reality–based physiological synchrony, this episode highlights HRV as a transdiagnostic marker of autonomic flexibility, resilience, and vulnerability.

Rather than treating HRV as a single “good or bad” number, this episode emphasizes context, interpretation, and clinical nuance. HRV is explored as a window into nervous system regulation across the lifespan and across settings, with implications for clinicians, researchers, and individuals alike.

Medical Disclaimer:
This podcast is for educational and informational purposes only and does not constitute medical advice. The information presented is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before making changes to medical care, mental health treatment, or lifestyle practices.

STUDIES DISCUSSED IN THIS EPISODE

1. Cardiovascular Disease and HRV (Review Article)

Full Title:
Heart rate variability in cardiovascular disease diagnosis, prognosis, and management

Authors:
Brian Xiangzhi Wang, MD
Ella Brennand, MD
Pierre Le Page, MD
Andrew R. J. Mitchell, MD, PhD

Affiliations:
Department of Medicine, Jersey General Hospital, St. Helier, Jersey
Department of Medicine, John Radcliffe Hospital, Oxford University Hospitals, Oxford, United Kingdom

Journal:
Frontiers in Cardiovascular Medicine
Section: Cardiac Rhythmology
Publication Date: January 26, 2026

Key Points:
• Reduced HRV is associated with arrhythmias, heart failure, ischemic heart disease, and post–myocardial infarction outcomes
• HRV may reveal early autonomic dysfunction before overt clinical symptoms
• Prognostic value of HRV remains debated due to mixed findings and methodological variability
• HRV shows promise for tracking recovery and monitoring comorbid conditions such as depression
• Wearable devices and machine learning may expand HRV’s clinical utility
• Major challenges include a lack of standardization and limited incremental predictive value over established risk factors

Article Link:
https://doi.org/10.3389/fcvm.2025.1680783

2. Allostatic Load, HRV, and Brain Networks

Full Title:
Linking allostatic load, heart rate variability and brain functional networks and structures in healthy men

Authors:
Juan M. Solano-Atehortua
Gabriel Castrillón
Jazmin X. Suarez-Revelo
Juan D. Sánchez-López
Daniel A. Vargas-Tejada
Valentina Hawkins-Caicedo
Juan C. Calderón
Jaime Gallo-Villegas
Yedselt V. Ospina-Serrano
Juan D. Caicedo-Jaramillo
Ana L. Miranda-Angulo

Journal:
Psychoneuroendocrinology
Publication Year: 2026

Key Points:
• Higher allostatic load is associated with lower HRV in healthy men
• A seven-biomarker allostatic load index (ALI-7) was positively associated with the LF/HF ratio
• Findings suggest increased sympathetic dominance with greater cumulative stress burden
• Brain functional connectivity and structure did not significantly moderate the HRV–allostatic load relationship
• ALI-7 may serve as an early marker of morbidity and mortality risk

Article Link:
https://doi.org/10.1016/j.psyneuen.2026.107759

3. HRV and Falls in Alzheimer’s Disease

Full Title:
Assessment of heart rate variability and occurrence of falls in Alzheimer’s disease: an exploratory study

Authors:
Evelize Antunes Rodrigues
Aline Roberta Danaga
Etiene Farah Teixeira de Carvalho
Carlos Alberto Santos Filho
José Burgos Ponce
Alessandro Ferrari Jacinto

Journal:
Arquivos de Neuro-Psiquiatria
Publication Date: January 25, 2026

Key Points:
• Older adults with Alzheimer’s disease showed greater autonomic dysfunction than controls
• Reduced parasympathetic activity and increased sympathetic dominance were observed
• Autonomic impairment was more pronounced during orthostatic challenge
• Alzheimer’s group experienced a higher incidence of falls
• Fall history was associated with HRV components

Article Link:
https://pmc.ncbi.nlm.nih.gov/articles/PMC12832160/

4. HRV Synchrony in Virtual Reality Collaboration

Full Title:
Remote collaboration in virtual reality induces physiological synchrony comparable to face-to-face interaction

Authors:
Stephan Streuber
Sarah Rogula
Maria Alejandra Quirós-Ramírez
Jens Pruessner

Journal:
Scientific Reports (Nature Portfolio)
Publication Date: January 27, 2026

Key Points:
• Physiological synchrony reflects implicit social and emotional alignment
• HRV synchrony was strong in face-to-face and immersive VR collaboration
• HRV synchrony was significantly weaker during video conferencing
• VR may support autonomic co-regulation and social cohesion

Article Link:
https://www.nature.com/articles/s41598-026-35955-y

5. HRV and Attention in Children with ADHD

Full Title:
Heart Rate Variability and MOXO d-CPT Relationship in Children with Attention Deficit Hyperactivity Disorder

Authors:
Sultan Tarlacı
Yaren Kaya Topal

Journal:
Applied Psychophysiology and Biofeedback
Publication Date: January 27, 2026

Key Points:
• Children with poorer MOXO performance showed higher sympathetic activation
• VLF power and SNS Index were the most robust HRV markers
• Traditional HRV metrics (SDNN, RMSSD) showed only modest, non-significant trends
• HRV may be useful for monitoring regulation and treatment response rather than diagnosis

Article Link:
https://link.springer.com/article/10.1007/s10484-026-09766-w

6. HRV Dynamics in Subjective Cognitive Decline

Full Title:
Cognitive changes and emotional heart rate variability dynamics in subjective cognitive decline: An exploratory longitudinal neuropsychophysiological study

Authors:
Giuseppina Elena Cipriani
Francesca Borghesi
Pietro Cipresso
Nicola Canessa
Sara Molfese
Cristiano Manco
Alice Chirico
Gloria Simoncini
Matteo Anselmino
Martina Amanzio

Journal:
Acta Psychologica
Publication Year: 2026

Key Points:
• HRV responses during emotional stimulation correlated with cognitive trajectories
• Changes in parasympathetic indices were associated with changes in cognition
• Findings align with neurovisceral integration models
• HRV may serve as an early psychophysiological marker of cognitive vulnerability

Article Link:
https://doi.org/10.1016/j.actpsy.2026.106308

This episode is sponsored by Optimal HRV.

Optimal HRV provides trauma-informed, research-based heart rate variability biofeedback tools for clinicians, researchers, and individuals. The platform integrates HRV assessment, guided breathing, biofeedback training, and professional education to support nervous system regulation and resilience.

Learn more at:
https://optimalhrv.com

Upcoming Event:
Biofeedback Federation of Europe (BFE) – 24th Annual Meeting

Dates:
March 23–28, 2026

Location:
Szczecin, Poland

Highlights:
• Six days of immersive workshops and scientific programming
• International faculty and networking opportunities
• Featured presenter: Dr. Inna Khazan
• Hands-on training in HRV biofeedback, neurofeedback, and applied psychophysiology

Registration:
https://bfemeeting.org

Dr. Jennifer S. Addleman, DO, CSCS, is a resident physician and certified strength and conditioning specialist (CSCS). She is currently completing her intern year in the Sutter Roseville Transitional Year Residency Program, followed by advanced training in Physiatry at the Stanford Physical Medicine and Rehabilitation Residency Program. Dr. Addleman is active in research involving gait analysis, wearable technology, and heart rate variability. She is passionate about exploring the applications of HRV across medicine and strength and conditioning.

Nicholas Lackey, PhD, BCB, is a Psychology Postdoctoral Resident with the Kaiser Permanente Mental Health Training Program in Northern California. He earned his PhD from Alliant International University in San Diego, during which he also completed the requisite experience for his Board Certification in Biofeedback. He explored research on meta-analyses and then on the implementation of Biofeedback. His dissertation explored the efficacy of a scale in examining types of chronic pain and Central Sensitization. Dr. Lackey aims to continue his career in Health Psychology and to examine the intersection of Psychology and Medicine through multidisciplinary collaboration and practice.

Here is their previous article on strength and conditioning training and heart rate variability mentioned in the episode: https://pubmed.ncbi.nlm.nih.gov/38921629/

In this episode of "This Week in HRV", Matt Bennett explores four recent studies that broaden our perspective on autonomic regulation across diverse physiological contexts. This week’s collection highlights the nuances of female reproductive physiology as captured by wearables, the specific cardiovascular mechanics of volitional sighing, the superior recovery potential of yoga practice, and the intricate neural coupling between the heart and brain during complex motor tasks. Together, these papers underscore the nervous system's adaptability to hormonal, behavioral, and cognitive demands.

1. Wearable-Derived Heart Rate Variability Across the Menstrual Cycle, Hormonal Contraceptive Use, and Reproductive Life Stages in Females: A Living Systematic Review

Authors: Eline de Jager, Brian Caulfield, Evgenia Angelidi, Brian MacNamee & Sinead Holden

Journal: Sports MedicineShutterstock

This systematic review aggregates data from wearable technology to map HRV trends across the female reproductive lifespan. The authors examine how natural menstrual cycle phases, hormonal contraceptives, and different reproductive stages influence autonomic metrics. The findings emphasize the importance of context when interpreting wearable data in females, as hormonal fluctuations drive distinct shifts in autonomic balance that must be distinguished from training load or stress.

https://link.springer.com/article/10.1007/s40279-025-02388-y

2. Dissecting Cardiovascular Responses to a Fixed-Interval Volitional Sighing Protocol Using a Mixed Modeling Approach

Authors: Neel Muzumdar, Kelly Sun, Samuel Zhang, Kelsey Piersol, Anthony P. Pawlak, Marsha E. Bates & Jennifer F. Buckman

Journal: Psychophysiology

Investigating the mechanics of breathwork, this study utilized a mixed modeling approach to analyze cardiovascular responses to a specific protocol of volitional sighing. The research dissects how fixed-interval sighing alters heart rate dynamics, providing granular insight into how this specific respiratory behavior—often used for acute stress relief—modulates autonomic output and cardiovascular stability. https://onlinelibrary.wiley.com/doi/10.1111/psyp.70235

3. Autonomic recovery following submaximal exercise in yoga practitioners versus aerobic and strength-trained individuals

Authors: Sreenath N., Pallavi L. C., Baskaran Chandrasekaran, Lavya Shetty, Lavina M. Manu & Shivaprakash Gangachannaiah

Journal: Annals of Physical and Rehabilitation Medicine

This comparative study assessed autonomic recovery speeds following submaximal exercise across three distinct groups: yoga practitioners, aerobic athletes, and strength-trained individuals. The results suggest that long-term yoga practice may confer a unique advantage in parasympathetic reactivation and in the speed of autonomic recovery post-exertion compared to traditional aerobic or resistance training backgrounds. https://www.tandfonline.com/doi/full/10.1080/07853890.2026.2615509

4. The interplay between cardiac and brain activities within a balancing skill-challenge context during goal-directed motor control

Authors: Heng Gu, Qunli Yao, Chao Yang, Zhaohuan Ding, Xiaoli Li & He Chen

Journal: Cerebral CortexGetty Images

Focusing on the brain-heart axis, this study explores the synchronization between cardiac rhythms and cortical activity during goal-directed motor control tasks requiring balance. The researchers identified a significant interplay between neural processing and heart rate variability, illustrating how the autonomic and central nervous systems couple to manage the cognitive and physical demands of complex motor skills. https://academic.oup.com/cercor/article-abstract/36/1/bhaf348/8430124

Sponsor

This episode of This Week in HRV is sponsored by Optimal HRV, supporting clinicians, educators, and organizations with evidence-based tools for nervous system regulation, HRV monitoring, and biofeedback-informed care.

Medical Disclaimer

This podcast is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional regarding diagnosis or treatment decisions.

In this episode of This Week in HRV, Matt Bennett explores five recent studies that deepen our understanding of heart rate variability as a marker of autonomic regulation across endocrine health, sleep physiology, theoretical neuroscience, extreme environmental exposure, and performance nutrition. Together, these studies illustrate how HRV reflects the nervous system’s capacity to integrate hormonal, behavioral, environmental, and recovery-related demands.

1. Comparative Analysis of Heart Rate Variability in Women with and Without Polycystic Ovary Syndrome (PCOS)

Authors: Sivaranjani; Prabhavathi; Keerthi; Bhavisha Sreenivasan; Thamarai Selvi; Saravanan; Panneerselvam
Journal: Journal of Pharmacy and Bioallied Sciences

This study examined resting heart rate variability in women with and without PCOS. Women with PCOS showed reduced HRV, reflecting diminished parasympathetic modulation and altered autonomic balance. The findings suggest that autonomic dysregulation may be present early in PCOS, even before overt cardiovascular disease develops.

https://journals.lww.com/jpbs/fulltext/2025/10000/comparative_analysis_of_heart_rate_variability_in.9.aspx

2. Autonomic Characteristics of Periodic Limb Movements: Comparison of Whole-Night and Stage N2 Linear and Non-Linear Heart Rate Variability

Authors: Elif Simin; Selahattin; Elif Göksu
Journal: Clinical Autonomic Research

Using overnight polysomnography, this study analyzed how periodic limb movements during sleep affect autonomic regulation. HRV analysis revealed transient sympathetic activation during limb movement events and reduced autonomic complexity across the night.

https://link.springer.com/article/10.1007/s10286-025-01184-y

3. Biofeedback from the Free Energy Principle Perspective: Some Psychoeducational and Clinical Implications

Author: Yossi
Journal: Biofeedback

This theoretical paper applies the Free Energy Principle to biofeedback practice, framing HRV biofeedback as a process of reducing physiological uncertainty and improving adaptive regulation.

https://biofeedback.kglmeridian.com/view/journals/biof/53/3/article-p47.xml

4. Autonomic Regulation across Sleep and Wake during an Antarctic Overwintering

Authors: C. Tortello; A. Folgueira; B. Cauda; L. E. González; E. Sala Lozano; N. Pattyn; G. Simonelli; S. A. Plano; D. E. Vigo
Journal: Scientific Reports

This study tracked heart rate variability across months in individuals overwintering in Antarctica, showing reduced parasympathetic activity, weakened circadian organization, and diminished sleep–wake autonomic differentiation during prolonged isolation.

https://www.nature.com/articles/s41598-025-31009-x

5. The Effects of an Acute Dose of Cannabidiol on Health and Two-Mile Time Trial Performance—A Pilot Study

Authors: Elyssa R., Brandon, Seth M., and Laura K.
Journal: Nutrients

This pilot study examined the effects of an acute cannabidiol dose on endurance performance and physiological markers. While performance did not improve, changes in autonomic recovery markers suggest CBD may influence post-exercise regulation.

https://www.mdpi.com/2072-6643/18/1/29

Sponsor

This episode of This Week in HRV is sponsored by Optimal HRV, supporting clinicians, educators, and organizations with evidence-based tools for nervous system regulation, HRV monitoring, and biofeedback-informed care.

Medical Disclaimer

This podcast is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional regarding diagnosis or treatment decisions.

In this episode of This Week in HRV, Matt Bennett explores five recent studies that deepen our understanding of heart rate variability across time, technology, cardiovascular health, brain aging, and addiction recovery. Together, these papers highlight both the strengths and limitations of HRV as a window into nervous system regulation.

1. Unveiling the Extremely Low Frequency Component of Heart Rate Variability

Authors: Krzysztof, Adam G.
Journal: Applied Sciences

This study demonstrates that ultra-low-frequency HRV is not a single physiological process, but can be decomposed into two independent components reflecting circadian and ultradian rhythms. The findings expand our understanding of long-term autonomic regulation and biological timing.

https://www.mdpi.com/2076-3417/16/1/426

2. Limited Evidence for Heart Rate Variability as a Predictor of Cognitive and Pathophysiological Brain Markers

Authors: Sofia, Jaime D., Arie, Balewgizie, Harriëtte, Rozemarijn, Rudi, Ronald, Peter Paul
Journal: Journal of Alzheimer’s Disease

Using a long-term longitudinal design, this study examined whether midlife HRV predicts later cognitive performance, brain imaging findings, or Alzheimer’s biomarkers. Results suggest HRV alone is not a reliable early predictor of neurodegenerative pathology.

https://journals.sagepub.com/doi/10.1177/13872877251409343

3. Beyond Motion Artifacts: Optimizing PPG Preprocessing for Accurate Pulse Rate Variability Estimation

Authors: Yuna, Natasha, Aarti, Varun, Matthew S.
Conference Proceedings: ACM (UbiComp)

This engineering study shows that preprocessing choices—particularly band-pass filtering—strongly influence the accuracy of pulse-rate variability derived from wearable PPG sensors. The authors demonstrate that adaptive preprocessing significantly improves HRV estimation accuracy.

https://dl.acm.org/doi/epdf/10.1145/3714394.3756241

4. Association of Diurnal Blood Pressure Patterns with Heart Rate Variability and Retinopathy in Patients with Essential Hypertension

Authors: Fengping, Hui, Tianfeng, Chen
Journal: Scientific Reports

This clinical study links abnormal nighttime blood pressure patterns with reduced HRV and a markedly higher prevalence of hypertensive retinopathy. The findings highlight the relationship between circadian autonomic regulation and microvascular health.

https://www.nature.com/articles/s41598-025-29694-9

5. Yoga for Opioid Withdrawal and Autonomic Regulation: A Randomized Clinical Trial

Authors: Suddala, Hemant, Bharath, Jayant, Ravindra P., Nishitha, Venkata Lakshmi, Urvakhsh Meherwan, Shivarama, Ganesan, Prabhat, Bangalore Nanjundiah, Kevin P., Matcheri, Pratima
Journal: JAMA Psychiatry

This randomized clinical trial shows that adding yoga to standard opioid detoxification significantly accelerates withdrawal recovery, improves HRV, reduces anxiety, improves sleep, and decreases pain—demonstrating the role of autonomic regulation in addiction recovery.

https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2843424

Sponsor

This episode of This Week in HRV is sponsored by Optimal HRV, supporting clinicians and organizations with evidence-based tools for nervous system regulation, HRV monitoring, and biofeedback-informed care.

Medical Disclaimer

This podcast is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional regarding diagnosis or treatment decisions.

Welcome to the first episode of 2026! Today, host Matt Bennett explores ten groundbreaking studies that bridge the gap between autonomic health, mental well-being, and physical performance. From the cardiac strain of early psychosis to the "neuroimmune triad" in diabetes, we dive deep into the latest science of Heart Rate Variability.

Detailed Study Summaries

1. Myocardial deformation and pro-arrhythmic indices in first-episode patients with psychosis before and one year after the initiation of antipsychotic treatment

Authors: Marios Plakoutsis, Aris Bechlioulis, Aidonis Rammos, Spyridon Sioros, Andreas Karampas, Georgios Georgiou, Lampros K. Michalis, Katerina K. Naka, and Petros Petrikis. This study highlights that a first psychotic episode is a full-body stressor causing immediate autonomic imbalance. Even without prior heart disease, patients showed abnormal HRV and subtle weakening of heart muscle contraction. While treatment rebalances the autonomic system, it requires vigilant monitoring due to medication-induced QT interval prolongation.

2. Perception of effort decreases with motor sequence learning

Authors: Bahram Ghafari Goushe, Thomas Mangin, Benjamin Pageaux, and Jason L. Neva. Learning a new skill isn't just a brain-based phenomenon. This experiment shows that as a task becomes automated, the body stays calmer (higher RMSSD) and the subjective perception of effort drops, reducing the physiological "price" of performance.

3. Serum cytokine levels and heart rate variability in the frequency domain in patients with chronic Chagas heart disease

Authors: Reinaldo B. Bestetti Sr., Renata Dellalibera-Joviliano, Milton Faria Junior, Rosemary A. Furlan Daniel, and Cláudia C. Domingos. Focusing on the inflammatory reflex, researchers found that Interleukin-23 (IL-23) specifically correlates with reduced vagal tone in Chagas heart disease, suggesting this cytokine interferes with the nervous system's ability to regulate the heart.

4. Research on changes in psychological, physical fatigue and emotional states in the National Youth Orienteering Preparation Camp

Authors: Haiyan Li. Comparing athletes at an intensive camp to those training at home, this study proves that structured recovery (fixed hydration, rest, and mental skills training) leads to significantly better HRV adaptations and lower cortisol, preventing burnout despite high training loads.

5. Autonomic-inflammatory crosstalk in diabetic atherogenesis: a neuroimmune triad (HRV-LMR-hsCRP) predicts carotid plaque risk in type 2 diabetes

Authors: Xinrui Zhou, Xiaowei Bai, Li Ding, Shuai Zhang, and Ya Li. This paper introduces a practical "neuroimmune triad"—combining HRV with immune markers (LMR and hsCRP)—to accurately predict the risk of carotid plaques in diabetic patients, identifying those at highest risk for stroke.

6. Effect of Tai Chi and Qigong on Heart Rate Variability: A Systematic Review and Meta-Analysis Examining Baseline Autonomic Function and Intervention Complexity as Moderators in Adults

Authors: Yasmine A. Gunawan, Mein-Woei Suen, Hanifa M. Denny, Ishita Chauhan, Milcha Fakhria, Siswi Jayanti, and Earl F.I. Mallari. A meta-analysis of 15 studies confirms that mind-body exercises improve HRV regardless of routine complexity. However, gains are largest for those who enter the practice with a relatively healthy baseline autonomic state.

7. Sympathovagal imbalance in drug-naïve chronic obstructive pulmonary disease patients: a physiological mechanism to cope with the severity of airway obstruction in an observational study

Authors: Durgesh K. Gupta, Shibu S. Awasthi, Suman Gupta, and Himani H. More. In COPD, the body reflexively boosts sympathetic drive to keep airways open (bronchodilation). This necessary coping mechanism leads to chronic autonomic imbalance, which explains the high cardiovascular risk in these patients.

8. Irritability in autism examined through network analysis of phenotypic and physiological correlates

Authors: Sara Alatrash, Tithi Paul, Brendan F. Andrade, Suneeta Monga, Jessica Brian, Evdokia Anagnostou, Melanie Penner, Atena Roshan Fekr, and Azadeh Kushki. Network analysis reveals that low HRV in autism serves as a marker for reduced regulatory capacity. When autonomic "brakes" are weak, children are more susceptible to the meltdowns associated with irritability.

9. A heart rate variability-driven framework for depression screening leveraging emotion-elicited autonomic divergence

Authors: Zhibin Zhu, Xuanyi Wang, Yifei Xu, Wanlin Chen, Jing Zheng, Shulin Chen, and Hang Chen. Researchers developed a "cardiac stress test" for mental health. By measuring HRV responses to sad stimuli, they identified depressed individuals with 77% accuracy—far more reliable than measurements taken during a neutral resting state.

10. Epidemiological Link Between Post-traumatic Stress Disorder and Cardiovascular Disease: Evidence, Mechanisms, and Clinical Implications

Authors: Malik K. Al-Ariki, Ivan Karpenko, Grigorii Esion, Anvar K. Djumanov, Shirin Dadaev, Hasan Saghir, Daria Khorunzhaya, Zlata Kurant, Valeriia Gevorgian, Anastasiia V. Badlaeva, Aleksey M. Kireychev, Mohammad Ayad, Haya Darwish, and Abubakar I. Sidik. This review argues that PTSD should be treated as a primary risk factor for heart disease. Chronic hyperarousal and inflammation in PTSD lead to a 60% higher risk of cardiovascular issues, necessitating integrated care between mental health and cardiology.

Research Links

1. First-Episode Psychosis: Journal of Psychiatric Research

2. Motor Sequence Learning: Scientific Reports

3. Cytokines & Chagas: Cureus

4. Youth Orienteering: Scientific Reports

5. Neuroimmune Triad: Cardiovascular Diabetology

6. Tai Chi & Qigong: Complementary Medicine Research

7. COPD HRV Imbalance: Cureus

8. Irritability in Autism: Scientific Reports

9. Depression Screening: Journal of Physiological Anthropology

10. PTSD & Heart Disease: Cureus

Episode Sponsor

Optimal HRV: Harness the power of your heart's data to manage stress and recovery. Download the Optimal HRV app or visit OptimalHRV.com to learn how you can integrate HRV tracking into your clinical practice or daily routine.

The Heart Rate Variability Podcast

In this special "Year in Review with a Twist," we shift our focus from the weekly news cycle to the big picture. We examine the most influential, highly cited research of 2024 to understand how these findings are revolutionizing clinical thinking and personal wellness in 2025.

HRV is no longer just a metric on a wearable; it has become the definitive framework for understanding resilience, adaptation, and human regulation.

Episode Highlights

• The Anxiety Biomarker: Why 2024 research confirms HRV as a "top-down" signal of how the brain calms itself and its potential for identifying anxiety subtypes.

• Combatting "Inflammaging": Exploring the link between vagal tone and chronic low-grade inflammation in aging populations.

• The Autonomic Conditioning of Exercise: How physical activity trains the nervous system, not just the heart muscle.

• Context is King: A deep dive into the 2024 "Sensitivity Review" highlighting how noise, heat, and even genetics must be accounted for in accurate readings.

• Biofeedback Frontiers: From COPD and Spinal Cord Injury to classroom attention, we look at how HRV training is breaking new ground in rehabilitation and education.

Key Research Reviewed

• Psychophysiology & Mental Health (2024): A landmark review synthesizing decades of data to establish HRV as a marker of prefrontal cortex regulation over the amygdala in anxiety disorders.

• Gerontology & Immunology (2024): Research into "Inflammaging," positioning HRV as a non-invasive biomarker for biological age rather than just chronological age.

• Sports Science & Performance (2024): A systematic review on HRV-guided training, emphasizing individual baselines over population norms for sustainable athletic performance.

• Clinical Biofeedback Trials (2024): Notable studies involving COPD patients and those with chronic spinal cord injuries, proving the feasibility of HRV training even in complex physiological cases.

• Neurodevelopmental Interventions (2024): Exploratory research into using HRV biofeedback for anxiety in Autism Spectrum Disorder and attention-building in school-aged children.

The 2025 Takeaway

"The question is no longer whether HRV is relevant, but how we apply it thoughtfully and responsibly. Autonomic flexibility is the foundation of emotional resilience, physical health, and cognitive performance."

Sponsor

This episode is brought to you by Optimal HRV. Bridge the gap between data and action with evidence-based tools designed for individuals, clinicians, and organizations. Explore our professional dashboards and HRV training e-gift cards today. Learn more at www.optimalhrv.com

Disclaimer: The information shared in this podcast is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before changing your health or wellness routines.

In this episode of The Heart Rate Variability Podcast – This Week in HRV, we expand the horizons of autonomic science. From the hidden impact of environmental pollutants to the neuro-spiritual connection of the "heart-brain axis," we examine how HRV serves as a vital bridge between our environment, our consciousness, and our clinical outcomes.

Episode Highlights

• Environmental Stressors: New research into how air pollution and lead exposure synergistically drive autonomic dysfunction.

• The Spirituality-HRV Link: Exploring Bayesian modeling of Heartbeat Evoked Potentials (HEP) as a biomarker for mental and spiritual wellbeing.

• HRV as a Clinical Life-Line: A deep dive into a major meta-analysis confirming HRV’s power to predict mortality in heart failure patients.

• Mapping Consciousness: How 24-hour HRV monitoring is helping clinicians differentiate between unresponsive wakefulness and recovery in patients with disorders of consciousness.

• Precision and Reliability: Critical insights into the reliability of short-term HRV measurements across different body positions and environments.

Featured Studies & Resources

Environmental Research (2025) — Air Pollution & Chronic Lead Exposure: The synergistic impact of environmental toxins on cardiac autonomic function. Link to Study

Cogent Psychology (2025) — Bayesian Modeling of HEP and HRV: An exploratory study on using HRV and heart-brain communication as biomarkers for spiritual health. Link to ResearchGate

Scientific Reports (2025) — The Multidimensional Perspective of HRV: A comprehensive look at the brain-heart axis (BHA) and its role in predicting multi-system disease. Link to Nature

Cureus (2025) — HRV as a Predictor of Mortality in Heart Failure: A systematic review and meta-analysis on the prognostic value of HRV in cardiovascular care. Link to Cureus

Scientific Reports (2025) — Clinical Reliability of Short-Term HRV Insights into the consistency of HRV measurements in dual-environment and dual-position settings. Link to Nature

Acta Neurologica Belgica (2025) — HRV in Disorders of Consciousness Using 24-hour HRV metrics to identify emergence from minimally conscious states (PMID: 41389121). Link to PubMed

Psicothema (2025) — Autonomic Modulation & Psychological States Examining the latest protocols for integrating HRV into psychological and behavioral health assessments. Link to ScienceDirect

Key Takeaway

The "Heart-Brain Axis" is more than a concept—it is a measurable reality. Whether we are assessing the impact of global environmental changes, the recovery of a patient’s consciousness, or the depth of a person’s spiritual wellbeing, HRV provides the high-fidelity data needed to understand the body's total adaptive capacity.

Sponsor

This episode is sponsored by Optimal HRV, providing evidence-based tools for measuring and training heart rate variability for individuals, clinicians, and organizations. Now offering e-gift cards for HRV training, app access, and professional dashboards.

Learn more at www.optimalhrv.com

In this episode of The Heart Rate Variability Podcast – This Week in HRV, we explore how the autonomic nervous system function connects metabolic disease, genetic disorders, targeted neural interventions, and the future of biofeedback science.

Episode Highlights

• How Metabolic Syndrome drives chronic sympathetic overactivation and reduced HRV

• Experimental evidence showing how the stellate ganglion block directly alters HRV and sympathetic tone

• New data validating dysautonomia in Ehlers–Danlos Syndrome using HRV and autonomic testing

• Why HRV is emerging as a critical clinical and research biomarker

• A preview of the 2026 AAPB Annual Scientific Meeting and why it matters for clinicians and researchers

Featured Studies & Resources

• Cureus (2025) — Autonomic Nervous System Dysregulation in Metabolic Syndrome
  https://www.cureus.com/articles/431819-autonomic-nervous-system-dysregulation-in-metabolic-syndrome-an-association-with-hypertension-and-cardiovascular-risk#!/

• Autonomic Neuroscience (2025) — Selective Sympathetic Action on HRV After Stellate Ganglion Block
  https://www.sciencedirect.com/science/article/abs/pii/S1566070225001298

• Cureus (2025) — Heart Rate Variability and Intrinsic Autonomic Coupling in Ehlers–Danlos Syndrome
  https://www.cureus.com/articles/429326-heart-rate-variability-and-intrinsic-autonomic-coupling-in-ehlers-danlos-syndrome?score_article=true#!/

• Association for Applied Psychophysiology and Biofeedback (AAPB)
  About AAPB: https://aapb.org/about
  2026 Annual Conference: https://aapb.starchapter.com/meetinginfo.php?id=43&ts=1763415344

Key Takeaway

Heart rate variability is a universal marker of resilience, translating metabolic stress, genetic vulnerability, and neural interventions into measurable physiological signals. HRV is no longer just a wellness metric—it's a clinical and scientific lens into autonomic health.

Sponsor

This episode is sponsored by Optimal HRV, providing evidence-based tools for measuring and training heart rate variability for individuals, clinicians, and organizations. Now offering e-gift cards for HRV training, app access, and professional dashboards.
Learn more at www.optimalhrv.com

Welcome to this week's exploration of the latest HRV science. In Episode 15, we discuss nine newly published studies that expand our understanding of HRV in mental health, physiology, chronic illness, and digital health innovation. This episode highlights remote biofeedback, pediatric heart dynamics, pregnancy and thyroid status, elite performance, cardiac rehabilitation, personalized training prediction, global research trends, autoimmune flare detection, and neurostimulation safety.

Featured Studies:

1. Remote HRV Biofeedback and Mental Health

   • “Efficacy and Methodology of Remote Heart Rate Variability Biofeedback Interventions for Mental Health: A Systematic Review and Meta-Analysis”

   • Vann-Adibe et al., Applied Psychophysiology and Biofeedback (2025)

   • https://link.springer.com/article/10.1007/s10484-025-09750-w

2. Pediatric HRV and Cardiac Complexity

   • “Age-dependent patterns of cardiac complexity unveiled by topological data analysis of pediatric heart rate variability”

   • Domínguez-Monterroza et al., PLOS ONE (2025)

   • https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0337620

3. Subclinical Hypothyroidism in Pregnancy and HRV

   • “Comparative Evaluation of Thyroid Profiles and Heart Rate Variability in Newly Diagnosed Subclinical Hypothyroid and Euthyroid Pregnant Women”

   • Singh et al., Cureus (2025)

   • https://www.cureus.com/articles/427419-comparative-evaluation-of-thyroid-profiles-and-heart-rate-variability-in-newly-diagnosed-subclinical-hypothyroid-and-euthyroid-pregnant-women?score_article=true#!/

4. Performance Optimization in Firefighters

   • “Mental imagery and breathing exercises integrated into a standardized warm-up routine enhance sympathetic activation and optimize muscular performance in firefighters”

   • Biéchy et al., PLOS ONE (2025)

   • https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0337431

5. Innovative Respiratory-Synchronized Pacemaker

   • University of Auckland research feature: “Pacemaker could help the heart heal”

   • Paton, Ben-Tal, Nogaret, and Stiles

   • https://www.auckland.ac.nz/en/news/2025/12/02/pacemaker-could-help-heart-heal.html

6. HRV and Personalized Fitness Modeling

   • “Advancing training effectiveness prediction in mass sport through longitudinal data: A mathematical model approach based on the Fitness-Fatigue Model”

   • Wang et al., PLOS ONE (2025)

   • https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0337824

7. Global Trends in HRV Research

   • “A Two-Decade Bibliometric Analysis of Heart Rate Variability Research (2005–2024)”

   • Sharma et al., Psychiatry Research (2025)

   • https://www.sciencedirect.com/science/article/pii/S1471015325001254?dgcid=author

8. Predicting Rheumatoid Arthritis Flares with Wearables

   • “Wearable devices detect physiological changes that precede and are associated with symptomatic and inflammatory rheumatoid arthritis flares”

   • Sharma et al., Scientific Reports (2025)

   • https://www.nature.com/articles/s41598-025-29748-y

9. Safety of Paired Associative Stimulation in SCI Rehab

   • “Heart rate variability in patients with incomplete spinal cord injury during a single session of paired associative stimulation”

   • Haakana et al., Scientific Reports (2025)

   • https://www.nature.com/articles/s41598-025-25802-x

Read the full article here: https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2025.1608442/full

Links & Resources Mentioned:

Clinical Psychiatry & Pharmacology

• Article: Which Antidepressants Shift Physiology? (Conexiant)
  • Takeaway: A look at how different antidepressant classes impact weight, blood pressure, and heart rate.
• Paper: Reducing Artifact Preprocessing in HRV-Based Personalized Psychosis Prediction (World Scientific)
  • Takeaway: Using AI to predict psychosis directly from wearable data.

Breathing & Interventions

• Paper: Light-guided resonant breathing enhances psychophysiological stress recovery in a simulated office environment (Nature Scientific Reports)
• Paper: Resonant breathing in hospitalised psychiatric patients with persistent somatic symptoms (General Psychiatry / BMJ)

The Science of Stress & Emotion (HRV)

• Paper: Measures of the psychophysiological response to recurrent anticipatory stress - the influence of neuroticism (Nature Scientific Reports)
• Paper: Heart rate variability reveals graded task difficulty effects and sensitization dynamics (Springer / J. Physiol. Anthropol.)
• Paper: HRV-Based Recognition of Complex Emotions: Feature Identification (MDPI Healthcare)

Physiology in Action (VR & Exercise)

• Paper: Impact of Stereoscopic Technologies on Heart Rate Variability in Extreme VR Gaming Conditions (MDPI Technologies)
• Paper: A controlled comparative study on the effect of arterial occlusion pressure on immediate sympathetic responses (Nature Scientific Reports)

1. Cardiac-vagal rhythm echoes on the heartbeat's mechanosensory imprint in the brain
   Candia-Rivera & Chavez — Communications Biology
   https://www.nature.com/articles/s42003-025-08969-x

2. Box breathing or six breaths per minute: Which strategy improves athletes' post-HIIT cardiovascular recovery?
   Kasap & Aydin — PLOS ONE
   https://doi.org/10.1371/journal.pone.0336615

3. The tolerance-related psychology and dynamic activity in the peripheral nervous system of Internet Gaming Disorder
   Chi & Hsiao — BioMedical Engineering Online
   https://biomedical-engineering-online.biomedcentral.com/articles/10.1186/s12938-025-01471-9

4. Heart rate variability biofeedback in adults with chronic spinal cord injury: a randomised feasibility study
   Schoffl et al. — BMC Neurology
   https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-025-04423-x

In this episode of The Heart Rate Variability Podcast, host Matt Bennett sits down once again with Stephanie White, HRV coach and educator known affectionately as “the HRV Guru.” Together, they dive deep into advanced heart rate variability concepts—especially heart rate fragmentation (HRF), very high frequency (VHF) activity, and new HRV metrics that can reveal hidden issues in autonomic health.

Stephanie shares insights from her work with clinicians, coaches, and patients—explaining why sometimes clients can’t reach the “Optimal Zone” in the Optimal HRV app and what physiological patterns might be behind it. She also outlines the importance of minerals, CO₂ balance, and careful data interpretation when working with HRV readings.

Key Topics Covered

• Stephanie’s Background – Her recovery journey from chronic illness using HRV biofeedback and her work with VCU’s Comprehensive Autonomic Center.

• Why HRV Data Sometimes “Doesn’t Make Sense” – How heart rate fragmentation can hijack HRV signals and confuse traditional measures like RMSSD.

• RMSSD vs. SDNN – Why SDNN may better capture resonance frequency breathing and coherent sine wave patterns.

• Understanding Heart Rate Fragmentation (HRF) – How alternating or sawtooth heart rhythms create misleading HRV statistics and mask underlying autonomic issues.

• Introducing “Very High Frequency (VHF)” – What happens when HRF shifts heart power above 0.4 Hz, and why current HRV software often misses it.

• The Role of CVNN and PSS – New or underused HRV metrics that can quantify fatigue, allostatic load, and fragmentation.

• Practical Clinical Applications – How coaches and clinicians can identify HRF, interpret data accurately, and help clients avoid “false high” HRV readings.

• Mineral Balance and HRV Health – Why calcium, sodium, potassium, and magnesium are crucial for healthy cardiac rhythm and recovery.

• Building an HRV Coaching Certification Pathway – Stephanie’s vision for “HRV Behavioral Health Coaches” and measurable, data-driven client progress.

Insomnia and HRV in Medical Students
Publication: Cureus
Title: “Insomnia and Its Impact on Psychomotor Reactivity, Autonomic Function, and Psychological Well-Being Among Medical Students: A Cross-Sectional Analytical Study”
Authors: Dhanusri, Rajalakshmi, Prakash, Bharadwaj, and Harichandrakumar
Key Finding: The severity of insomnia among medical students was associated with slower reaction times and higher psychological distress, while short-term resting HRV remained largely unchanged. Early cognitive and mood changes appear before resting HRV declines, underscoring that subjective fatigue and attention lapses can be earlier indicators than RMSSD or SDNN.
Link: https://www.cureus.com/articles/427559-insomnia-and-its-impact-on-psychomotor-reactivity-autonomic-function-and-psychological-well-being-among-medical-students-a-cross-sectional-analytical-study#!/

Meta-Analysis: HRV in Insomnia Disorder
Publication: Sleep and Breathing
Title: “Heart rate variability in patients with insomnia disorder: a systematic review and meta-analysis”
Authors: Zhao and Jiang
Key Finding: Across 17 studies and 921 participants, insomnia showed only mild, non-significant reductions in HRV measures such as SDNN and HF-norm. The review emphasizes methodological variability and suggests that chronic insomnia’s autonomic signature is subtle and context-dependent.
Link: https://link.springer.com/article/10.1007/s11325-022-02720-0

Sleep Deprivation and HRV
Publication: Frontiers in Neurology
Title: “Effects of Sleep Deprivation on Heart Rate Variability: A Systematic Review and Meta-Analysis”
Authors: Zhang, Niu, Ma, Wei, Zhang, and Du
Key Finding: Eleven trials revealed consistent sympathetic dominance after sleep deprivation, as evidenced by decreased RMSSD, increased LF and LF/HF, and stable SDNN. These findings reinforce that RMSSD is the most sensitive marker of HRV for acute sleep loss and stress load.
Link: https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2025.1556784/full

COMISA: Insomnia and Sleep Apnea Combined
Publication: Scientific Reports
Title: “Heart Rate Variability Analysis in Comorbid Insomnia and Sleep Apnea (COMISA)”
Authors: Martín-Montero, Vaquerizo-Villar, García-Vicente, Gutiérrez-Tobal, Penzel, and Hornero
Key Finding: Using over 5,000 overnight ECGs, COMISA patients showed reduced parasympathetic tone while awake and increased sympathetic drive during sleep. This dual imbalance likely explains elevated cardiovascular risk when both disorders coexist.
Link: https://www.nature.com/articles/s41598-025-02541-7

Depression and HRV in Students
Publication: Kompasiana
Title: “Diagnosis of Depression Based on SDNN Indicator of Heart Rate Variability (HRV) in Students”
Author: Widya P.
Key Finding: In 120 university students aged 18–25, PHQ-9 depression scores correlated negatively with SDNN (r = –0.48, p < 0.001). An SDNN threshold of 50 ms identified moderate-to-severe depression with 82% sensitivity and 77% specificity, suggesting SDNN as a potential physiological adjunct to psychological screening.
Link: https://www.kompasiana.com/ola7155/690eaadfed641503d4754d93/diagnosis-of-depression-based-on-sdnn-indicator-of-heart-rate-variability-hrv-in-students#google_vignette

Post-PCI Inflammation and Wearable Data Integration
Publication: PLOS ONE
Title: “Multi-modal inflammatory risk modeling in post-PCI patients using behavioral and physiologic data”
Author: Sanghee Kim
Key Finding: In 312 post-PCI patients, combining wearable data (steps, sleep efficiency, HRV, SpO₂) with inflammatory biomarkers improved the prediction of hs-CRP reduction. The Transformer-based model achieved an AUC of 0.88, identifying step count and HRV as leading behavioral predictors of inflammation control.
Link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0336394

Sponsor Spotlight

Optimal HRV — The app designed to make HRV tracking practical.
The latest update introduces full multilingual support (17+ languages), a smoother onboarding process, guided device testing, and enhanced mindfulness playback.
Recognition: 2026 Edison Awards Nominee for Innovation.
Learn more: Search “Optimal HRV” in your app store.

1. HRV Biofeedback for PTSD & Chronic Pain

   • Publication: Journal of Affective Disorders

   • Title: "Heart rate variability biofeedback improves co-occurring posttraumatic stress disorder and chronic pain symptoms: A randomised waitlist controlled trial"

   • Key Finding: This is the first RCT for this co-occurring population. Just six weeks of HRV biofeedback (HRVBF) led to a 24.3% decrease in PTSD symptoms and a 24.9% reduction in pain interference.

2. Biofeedback in Pediatric Care

   • Publication: Cleveland Clinic ConsultQD

   • Title: "Biofeedback Interventions With Psychotherapy in Pediatric Care: The Present and the Future"

   • Key Finding: A clinical guide and call to action for integrating biofeedback (like HRV) with psychotherapy to make self-regulation a concrete, measurable skill for children (e.g., pairing HRV biofeedback with exposure therapy for phobias).

3. Slow-Paced Contraction (SPC)

   • Publication: Biosourcesoftware.com

   • Title: "Add Slow-Paced Contraction to Your Practice"

   • Key Finding: This article details the "how-to" for Slow-Paced Contraction, a vital alternative to slow-paced breathing for patients with contraindications (like severe COPD, kidney disease, or metabolic acidosis).

4. Tai Chi & HRV

   • Publication: Medicine

   • Title: "Effects of a Tai Chi dance intervention on the autonomic nervous system in university students"

   • Key Finding: A 16-week Tai Chi intervention was shown to be an effective method to prevent excessive declines in resting HRV in university students, building autonomic resilience.

5. HRV & Non-Suicidal Self-Injury (NSSI)

   • Publication: Taylor & Francis Online

   • Title: "Association between heart rate variability and emotion dysregulation in adolescents with non-suicidal self-injury"

   • Key Finding: This review frames reduced HRV as a key physiological marker of the Emotion Dysregulation and autonomic imbalance that underlies the distress leading to NSSI in adolescents.

6. HRV in IPV Offenders

   • Publication: Journal of Criminal Justice

   • Title: "Diminished vagally mediated heart rate variability in a compassion-eliciting task in intimate partner violence offenders"

   • Key Finding: Intimate Partner Violence (IPV) offenders showed lower vagally mediated HRV during a compassion-eliciting task, suggesting a diminished physiological capacity to connect with others' suffering.

7. HRV & Heart Failure (HFrEF)

   • Publication: Current Cardiology Reviews (via PMC)

   • Title: "Heart Rate Variability and Heart Failure with Reduced Ejection Fraction: A Systematic Review of Literature"

   • Key Finding: A systematic review concluding that autonomic impairment (low HRV) is a hallmark of HFrEF and that abnormally low HRV metrics are a powerful predictor of worse prognosis.

8. HRV & Subclinical Thyroid Dysfunction

   • Publication: Egyptian Journal of Radiology and Nuclear Medicine

   • Title: "Heart rate variability and left atrial stiffness index... in subclinical thyroid dysfunction"

   • Key Finding: Even subclinical thyroid disorders are linked to increased left atrial stiffness (heart stress). The subclinical hyperthyroid group also showed a significantly increased LF/HF ratio, indicating sympathetic dominance.

9. Predicting Vasovagal Syncope

   • Publication: European Heart Journal

   • Title: "An autonomic function-based prediction model for cardioinhibitory vasovagal syncope"

   • Key Finding: Standard HRV metrics could not differentiate syncope subtypes, but a related metric, Deceleration Capacity (DC), was a significant predictor, leading to a functional predictive model.

10. HRV at High Altitude

    • Publication: Journal of Family Medicine and Primary Care

    • Title: "Normative data of heart rate variability in healthy populations residing at high altitudes..."

    • Key Finding: This study establishes new HRV norms for a population living at 3500m, confirming their values differ from sea-level norms. It also found higher parasympathetic tone (RMSSD, pRR50) in females than males.

11. HRV & Cognitive Workload

    • Publication: BMC Nursing

    • Title: "An integrative review of cognitive workload assessment for safety management"

    • Key Finding: This review identifies ECG (for HRV), EEG, and EOG as the top three preferred physiological signals for objectively assessing cognitive workload in real-time, moving beyond subjective surveys.

12. HRV & Shamanic Journeying

    • Publication: Frontiers in Psychology

    • Title: "Dynamic changes in cardiac function during shamanic journeying and Qigong meditation"

    • Key Finding: A fascinating single-case study tracking HRV during shamanic states. Shamanic drumming, for example, decreased heart rate but increased parasympathetic metrics (RMSSD, pNN50), showing a unique physiological profile.

Episode Summary

In this insightful episode of The Heart Rate Variability Podcast, host Matt Bennett sits down with Dr. David Eddie, a clinical psychologist and researcher at Massachusetts General Hospital and Assistant Professor at Harvard Medical School. Together, they explore how Heart Rate Variability (HRV) is transforming the landscape of addiction recovery, psychotherapy, and digital mental health.

Dr. Eddie shares how HRV can serve as both a biomarker for relapse risk and a tool for emotional regulation, shedding light on how AI, wearable technology, and stress-detection algorithms could revolutionize real-time intervention in substance use treatment.

Listeners will gain a deeper understanding of how HRV biofeedback, digital monitoring, and personalized algorithms can support clients in recovery, enhance self-awareness, and inform clinicians’ decision-making in psychotherapy.

Key Topics Covered

• How Dr. David Eddie began his HRV journey during graduate research at Rutgers and the Recovery Research Institute.

• HRV as a biomarker for pathology and relapse risk in substance use disorder and mental health conditions.

• Developing stress-detection algorithms that leverage real-time HRV data through wearables and AI.

• Challenges of variability and individual differences in HRV data across populations.

• Integrating ecological momentary assessment (EMA) and ambulatory psychophysiological monitoring for clinical insights.

• How HRV biofeedback supports recovery and emotional regulation in psychotherapy and addiction treatment.

• Ethical and practical issues around proprietary algorithms, data transparency, and commercial wearables.

• The future of HRV research, AI integration, and passive monitoring in clinical psychology.

Key Takeaways

• HRV is both a symptom and contributor to addiction and mental health challenges, offering potential for early detection of relapse risk.

• Wearables and AI can help clinicians intervene in real time — possibly preventing relapse or emotional crises before they occur.

• Personalized baselines and individual calibration are essential to improve algorithm accuracy for diverse populations.

• HRV biofeedback provides an accessible, evidence-based method to help clients build resilience, reduce craving, and regulate their nervous system.

• Future advances will make passive, scalable HRV monitoring a core element of digital mental health and recovery care.

About the Guest

Dr. David Eddie is a clinical psychologist and researcher at Massachusetts General Hospital’s Recovery Research Institute and the Center for Digital Mental Health, as well as an Assistant Professor of Psychiatry at Harvard Medical School. His work focuses on addiction recovery, psychophysiology, and integrating HRV into digital and clinical interventions.

Follow his work at Recovery Research Institute or through Harvard Medical School publications.

Resource 1:

Title: Associations between mental health disorder symptoms and cardiac function among Royal Canadian Mounted police cadets during the Cadet training program

Authors: R.N. Carleton, T.A. Teckchandani, J.P. Neary, J.E. Samayoa, J.M.B. Khoury, K.Q. Maguire, G.P. Krätzig, & G.J.G. Asmundson

Publication: Journal of Psychiatric Research

Link: https://www.sciencedirect.com/science/article/pii/S0022395625006521

Resource 2:

Title: Transgenerational effects of violence in adolescents exposed to grandmaternal intimate partner violence during pregnancy: Heart rate variability and DNA methylation

Authors: Nayara Cristina dos Santos Oliveira, Aline Furtado Bastos, Fernanda Serpeloni, & Simone Gonçalves de Assis

Publication: Behavioural Brain Research

Link: https://www.sciencedirect.com/science/article/abs/pii/S0166432825004735

Resource 3:

Title: The role of separation anxiety and autonomic dysregulation in pediatric vasovagal syncope. A cross-sectional study

Authors: Gaia Cuzzocrea, Andrea Fontana, Cristiana Alessia Guido, Marta Mascanzoni, Alberto Spalice, Camilla Guccione, Angelos Halaris, Stephen Porges, Lucia Sideli, & Vincenzo Caretti

Publication: Journal of Psychiatric Research

Link: https://www.sciencedirect.com/science/article/abs/pii/S0022395625006351

Resource 4:

Title: Acute cardiovascular and cerebral blood flow responses to high-frequency, low-amplitude vibration on the neck

Authors: Viet Q Dinh, Malinda Hansen, K Austin Davis, Lindsey Peralez, & Caroline A Rickards

Publication: Journal of Applied Physiology (via PMC)

Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12551627/

Resource 5:

Title: Autonomic Flexibility and Early Treatment Success: Heart Rate Variability Predicts Remission in First-Episode Psychosis

Authors: Judith Rohde, Samantha Weber, Mateo de Bardeci, Aygün Ertuğrul, Grammato Amexi, Eva Schultz, & Sebastian Olbrich

Publication: Schizophrenia Bulletin

Link: https://academic.oup.com/schizophreniabulletin/advance-article/doi/10.1093/schbul/sbaf191/8305265?login=false

Resource 6:

Title: Interplay between key metabolic hormones, metabolic factors, renal function, and heart rate variability in humans with obesity

Authors: Kitchaya Pongwattanapakin, Chit Care, Chantacha Sitticharoon, Kittikorn Tommy Wilasrusmee, Issarawan Keadkraichaiwat, Pailin Maikaew, & Rungnapa Sririwichitchai

Publication: Scientific Reports

Link: https://www.nature.com/articles/s41598-025-21757-1

Resource 7:

Title: Metabolic Minute – Heart Rate Variability

Authors: WCCB Web Staff (featuring Dr. Gary Rolband, Stephen Gage, and Matt Bennett)

Publication: WCCB Charlotte

Link: https://www.wccbcharlotte.com/2025/10/27/metabolic-minute-heart-rate-variability/

Resource 1:

Title: Top 50 scariest movies of 2025 (and Fright Night Physiology)

Publication: WISN.com / Science of Scare Project

Link: https://www.wisn.com/article/top-50-scariest-movies-2025/69140286

Resource 2:

Title: Heart Rate Variability as a Key to Regulation and Stress

Author: D. N. Solomon

Publication: Psychology Today

Link: https://www.psychologytoday.com/us/blog/the-narrative-nurse-practitioner/202412/heart-rate-variability-as-a-key-to-regulation-and

Resource 3:

Title: Haunted House, Healthy Heart

Publication: Business Health Trust

Link: https://businesshealthtrust.com/news_insights/haunted-house-healthy-heart/

Resource 4:

Title: Why Do We Love Being Scared? The Science Behind Horror Movies

Author: A. Bennett

Publication: Promega Connections

Link: https://www.promegaconnections.com/the-science-behind-horror-movies/

Resource 5:

Title: Playing With Fear: A Field Study in Recreational Horror

Authors: M. M. Andersen, A. Coltan, et al.

Publication: PMC (via Emotion)

Link: httpss://pmc.ncbi.nlm.nih.gov/articles/PMC7734554/

Resource 6:

Title: Scared together: Heart rate synchrony and social closeness in a high-intensity horror setting

Authors: M. M. Andersen, et al.

Publication: PubMed (via Psychological Science)

Link: https://pubmed.ncbi.nlm.nih.gov/40720311/

Resource 7:

Title: I tracked my heart rate through the 10 haunted houses of Halloween Horror Nights...

Author: K. Weekman

Publication: Yahoo.com

Link: https://www.yahoo.com/entertainment/article/i-tracked-my-heart-rate-through-the-10-haunted-houses-of-halloween-horror-nights-heres-what-scared-me-most-180025551.html

Resource 1:

Title: Pleasant odors specifically promote a soothing autonomic response and brain–body coupling through respiratory modulation

Authors: Valentin Ghibaudo, Matthias Turrel, Jules Granget, Maëlys Souilhol, Samuel Garcia, Jane Plailly & Nathalie Buonviso

Publication: Scientific Reports

Link: https://www.nature.com/articles/s41598-025-20422-x

Resource 2:

Title: Improved non-invasive detection of sleep stages when combining skin sympathetic nerve activity and heart rate variability analysis with AI

Authors: Md. Aktaruzzaman & Thomas H. Everett IV

Publication: Scientific Reports

Link: https://www.nature.com/articles/s41598-025-20282-5

Resource 3:

Title: Increased sleep apnea-specific hypoxic burden is independently associated with cardiovascular autonomic dysfunction in obstructive sleep apnea: A large-scale study

Authors: Chenyang Li, Zhenger Zhou, Xiaozhen Zhang, Enhui Zhou, Tianjiao Zhou, Jingyu Zhang, Xinyi Li, Jianyin Zou, Huajun Xu, Jian Guan, Yupu Liu, Suru Liu, Xiaoyue Zhu, Weijun Huang, Hongliang Yi, Shankai Yin

Publication: Sleep Medicine

Link: https://www.sciencedirect.com/science/article/abs/pii/S1389945725005386

Resource 4:

Title: Strengthening the heart by means of a gratitude intervention?

Authors: Andreas R. Schwerdtfeger, Claudia Traunmüller, Bernhard Weber & Christian Rominger

Publication: The Journal of Positive Psychology

Link: https://www.tandfonline.com/doi/full/10.1080/17439760.2025.2574048?af=R#abstract

Resource 5:

Title: Child and marital stress are associated with a psychophysiological index of self-regulatory capacities among parents of preschool children

Authors: Sasha MacNeil, Chelsea da Estrela, Warren Caldwell, Jean-Philippe Gouin

Publication: International Journal of Psychophysiology

Link: https://www.sciencedirect.com/science/article/pii/S0167876025007470?via%3Dihub

Resource 6:

Title: Factors influencing heart rate variability in nurses following night shifts: a prospective observational clinical study

Authors: Taihe Zhan, Ziying Zhang, Zhimin Shi, Hongyan Xie, Daogang Zha & Xiumei Wei

Publication: BMC Nursing

Link: httpsD://bmcnurs.biomedcentral.com/articles/10.1186/s12912-025-03975-0

Resource 7:

Title: Heart Rate Variability Biofeedback and Mental Stress Myocardial Flow Reserve: A Randomized Clinical Trial

Authors: Amit J. Shah, Paolo Raggi, Hua She, et al.

Publication: JAMA Network Open

Link: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2840378

Resource 8:

Title: VCU research in action: Teaching patients to take a deep breath

Author: Olivia Trani

Publication: VCU News

Link: https://news.vcu.edu/article/2025/10/vcu-research-in-action-teaching-patients-to-take-a-deep-breath

In this solo episode of the Heart Rate Variability Podcast, Matt Bennett explores the science and practicality of resonance frequency breathing, a term he notices is often misused. He introduces his AI counterpart, AI Matt, to present the research on resonance frequency breathing, which involves finding a natural rhythm for breathing that aligns with the body's optimal pace. Matt aims to delve into the correct usage of this term, discuss its scientific basis, and share practical applications in the episode.

Resonance Frequency Breathing Techniques

Matt discussed resonance frequency breathing, explaining that while 6 breaths per minute is often cited, the actual rate can vary based on factors like height. He noted that trained biofeedback practitioners have observed rates as low as 3.5 breaths per minute in special operators and professional athletes. Matt emphasized the importance of synchronization between the heart, breath, and nervous system, as well as the impact on brain functioning.

Resonance Frequency Breathing Assessment

Matt discussed the concept of resonance frequency breathing, noting that while research suggests an average of 6 breaths per minute, individual rates can vary widely. He explained that resonance frequency assessments involve gradually reducing breathing rate from 7 to 3.5 breaths per minute to find the rate that maximizes HRV. Matt emphasized that while height may influence resonance frequency, factors like fitness and body mass could also affect it, particularly for former athletes. He recommended practicing paced breathing before taking the assessment and suggested that repeated testing might show small changes in breathing rate over time.

Breathing Patterns and Resonance Frequency

Matt discussed the importance of regularly reassessing one's resonance frequency breathing to ensure accuracy, especially if consistent readings are obtained over several months without significant lifestyle changes. He shared his personal experience with adjusting his breathing patterns, including experimenting with a 4.5 to 3.5 breaths per minute rate and a 2:1 inhale-to-exhale ratio, inspired by recent research suggesting extended exhales can improve low-frequency heart rate variability. Matt emphasized the significance of personalized assessments using tools like the OptimalHRV app to determine optimal breathing patterns and encouraged others to explore different breathing techniques for maximum impact.

Residence Frequency Breathing Assessment

Matt discussed the importance of practicing residence frequency breathing assessment and emphasized the value of this technique in maximizing breathwork practices. He noted that while the concept is gaining recognition among fitness influencers and in peer-reviewed research, the full impact of the science is often overlooked in blog posts. Matt planned to include relevant research in the show notes and promised to cover this topic further in the next episode.

Resource 1:

Title: The relationship between heart rate variability and affective disorders: associations with symptomatic improvement and therapeutic alliance

Authors: Alexandra F. Gonçalves, Eugénia Ribeiro, Adriana Sampaio, Natividade S. Couto-Pereira, Pedro Moreira & Joana F. Coutinho

Publication: BMC Psychology

Link: https://bmcpsychology.biomedcentral.com/articles/10.1186/s40359-025-02960-1

Resource 2:

Title: Development and validation of the socio-evaluative N-back task to investigate the impact of acute social stress on working memory

Authors: Matthias Haucke, Sabrina Golde & Stephan Heinzel

Publication: Scientific Reports

Link: https://www.nature.com/articles/s41598-025-22611-0

Resource 3:

Title: Panic Attack Prediction for Patients With Panic Disorder via Machine Learning and Wearable Electrocardiography Monitoring: Model Development and Validation Study

Authors: Hayoung Oh, Hunmin Do, Chaehyun Maeng, Jinsuk Park, Taejun Yoon, Jihwan Kim, Hyeran Hwang, Seoin Choi, & Piao Huilin

Publication: Journal of Medical Internet Research

Link: https://www.jmir.org/2025/1/e69045

Resource 4:

Title: Non-invasive cardiovascular risk stratification in type 2 diabetes: a pulse wave and pulse rate variability analysis with machine learning

Authors: Saurav Kumar, Apakrita Tayade, Amber Shrivastava, & Ravi Bhallamudi

Publication: Biomedical Signal Processing and Control (via Science Direct)

Link: https://www.sciencedirect.com/science/article/abs/pii/S1746809425014491

Resource 5:

Title: How Tracking Your Health Metrics Can Help You Live Longer

Author: Alice Park (Interview with Zahi Fayad)

Publication: TIME

Link: https://time.com/7324741/health-metrics-tracking-live-longer/

Resource 6:

Title: Stressed at Work? Your Heart Disease Risk Just Jumped 50%. Here’s the One Number That Shows How to Fight Back

Author: Julien Raby

Publication: BoxLife Magazine

Link: https://boxlifemagazine.com/boost-heart-resilience-by-tracking-hrv/

Resource 7:

Title: “Resonance Breathing” Is The Anti-Stress Hack You Can Do Anywhere

Author: Carolyn Steber

Publication: Bustle

Link: https://www.bustle.com/wellness/resonance-frequency-breathing-stress-hack

• Personalized Respiratory Guidance for HRV: Lin, Z., Kong, W., Qiu, S., Luo, M., Wei, J., Guo, X., ... & Dan, G. (2025). High-precision personalized respiratory guidance model for enhanced breathing training: effects on heart rate variability. Biomedical Signal Processing and Control, 100, 108720.
  • https://www.sciencedirect.com/science/article/abs/pii/S1746809425012315
• Therapy with Local Anesthetics and HRV: Weinschenk, S., Topbas-Selcuki, N. F., Benrath, J., Strowitzki, T., & Feisst, M. (2025). Effects of therapy with local anesthetics (TLA) on heart rate variability (HRV) over 24 hours. Chronobiology International.
  • https://www.tandfonline.com/doi/full/10.1080/07420528.2025.2560963?src=exp-la
• Veterans, Service Dogs, and HRV: Krause-Parello, C. A., Friedmann, E., Taber, D., Zhu, H., Quintero, A., & Yount, R. (2025). Veterans Training Service Dogs for Other Veterans: An Animal-Assisted Intervention for Post-Traumatic Stress Disorder. Behavioral Sciences, 15(9), 1180.
  • https://www.mdpi.com/2076-328X/15/9/1180
• Circadian Rhythm of HRV in Pregnancy: Rasouli, M., Feli, M., Azimi, I., Haghayegh, S., Sarhaddi, F., Niela-Vilen, H., ... & Rahmani, A. M. (2025). Circadian rhythm of heart rate and heart rate variability in pregnancy. npj Women's Health, 3(1), 57.
  • https://www.nature.com/articles/s44294-025-00107-6
• Wearable Tech in Tennis Players: Wang, Z. (2025). Integration of wearable technologies in monitoring physical performance and psychological stress in tennis players. Acta Psychologica, 260, 105706.
  • https://www.sciencedirect.com/science/article/pii/S0001691825010194
• Acoustic Features of Chants: Dolan, E. W. (2025, October 6). Chants across cultures share features that promote relaxation. PsyPost.
  • https://www.psypost.org/chants-across-cultures-share-features-that-promote-relaxation/

Understanding Frequency Domains in HRV

Dr. Khazan begins by breaking down the concept of frequency domains in HRV. Just as white light contains multiple colors, the heart rate signal is composed of several distinct frequency components. Using tools like the Fast Fourier Transform, researchers can separate heart signals into high-frequency, low-frequency, and very-low-frequency ranges — each linked to specific physiological processes and parts of the autonomic nervous system.

Low Frequency HRV and the Baroreflex

The conversation dives deep into low-frequency power, which represents the interplay between the baroreflex (the body’s blood pressure regulation system) and the vagus nerve. Dr. Khazan explains how resonance-frequency breathing—typically practiced for 20 minutes a day—acts like strength training for these systems. Over time, this practice enhances emotional regulation, stress recovery, and overall heart-brain coherence.

Why Breathing Rate and Context Matter

Listeners learn that breathing too long in a low-frequency state can actually suppress other important HRV components, such as high-frequency and very-low-frequency power. Instead, Dr. Khazan recommends brief, consistent training sessions to balance all aspects of the nervous system. She also clarifies common misconceptions, including the outdated idea that low-frequency HRV measures sympathetic activity, emphasizing instead its parasympathetic and baroreflex origins.

Making Sense of HRV Metrics in Optimal HRV

Matt and Dr. Khazan discuss Optimal HRV’s “Optimal Zone” scale, which tracks the percentage of time users spend in low-frequency dominance during a session. They also unpack metrics like Max-Min and total low-frequency power, explaining how they interact and what each reveals about training efficiency and day-to-day readiness.

Practical Takeaways

• Practice resonance-frequency breathing for 20 minutes a day to enhance self-regulation.

• Avoid over-training in the low-frequency zone — balance is key.

• Understand that low-frequency HRV is not a measure of stress or sympathetic activity, but rather a reflection of vagal and baroreflex strength.

• Leverage your Optimal HRV app metrics to track progress, focus, and nervous-system adaptability.

Listen & Learn More

Explore more insights from Dr. Khazan and Matt Bennett on heart rate variability, stress regulation, and biofeedback science.

Visit OptimalHRV.com for resources, show notes, and upcoming episodes, including the "This Week in HRV" series, which highlights the latest HRV research and applications.

Research Studies:

1. Multisensory environmental effects on HRV and psychological restoration – Scientific Reports
2. Walking through green and grey: Exploring sequential exposure and multisensory environmental effects on psychological restoration – Building and Environment
3. The Impact of Vipassana Meditation on Health and Well-being: A Systematic Review of Current Evidence – Cureus
4. Cardiac timing effects on response speed are modulated by blood pressure, but not by heart rate variability, in healthy young adults – Physiological Reports
5. Heart-brain interaction in emotional regulation – Scientific Reports
6. Environmental stress and HRV in agricultural settings – Agricultural and Forest Meteorology
7. HRV and emotion regulation in depression risk – JAMA Psychiatry
8. HRV modulation through breathing and neural coherence – Frontiers in Human Neuroscience

News and Features:

1. Professor honored for pioneering heart–brain research – UC Irvine News
2. Solo practitioner uses HRV tech to improve patient care – Healthcare IT News
3. What is heart rate variability and how can it guide smarter leadership decisions – Manila Bulletin
4. HRV: The new secret weapon for heart resilience – Men’s Health

Each of these studies and stories offers a unique perspective on how HRV connects the heart, brain, and body. For more insights, visit our website and subscribe to weekly updates on the evolving science of heart rate variability.

We’ll explore:

• How brain networks and cognitive load shape HRV readings.
  
• Why slow breathing alone is powerful, and what feedback really adds.
  
• The Benefits of Yoga Nidra for Patients Recovering from Coronary Artery Bypass Surgery.
  
• How walking in natural environments provides a stronger autonomic boost than indoor or urban exercise.
  
• Real-world HRV findings in emergency medicine and why lab results don’t always translate.
  
• How pollution, heat, and noise suppress vagal tone.
  
• New frontiers in dynamic and multimodal HRV metrics.
  
  

As always, I’ll connect the research to practical, client-ready strategies you can use right away.

This podcast is sponsored by Optimal HRV. Learn more at optimalhrv.com.

References 

1. Behavioural Brain Research – Neural and cognitive influences on autonomic function. https://doi.org/10.1016/j.bbr.2025.115811
   
   
2. Psychophysiology – Comparing HRV biofeedback and slow-paced breathing. https://doi.org/10.1111/psyp.70156
   
   
3. Cureus – Impact of Yoga Nidra on heart rate variability in coronary artery disease patients undergoing coronary artery bypass grafting. https://www.cureus.com/articles/402202-impact-of-yoga-nidra-on-heart-rate-variability-in-coronary-artery-disease-patients-undergoing-coronary-artery-bypass-grafting-a-comparative-study
   
   
4. Psychology of Sport and Exercise – Green exercise randomized controlled trial. https://doi.org/10.1016/j.psychsport.2025.102883
   
   
5. International Journal of Emergency Medicine – HRV in emergency medicine contexts. https://intjem.biomedcentral.com/articles/10.1186/s12245-025-00967-4
   
   
6. Environmental Research – Environmental stressors and their impact on HRV. https://doi.org/10.1016/j.envres.2025.122895
   
   
7. Preprint manuscript – Multimodal HRV analytics integrating respiration, voice, and movement. https://pmc.ncbi.nlm.nih.gov/articles/PMC8401087/#:~:text=HRV%20analysis%20is%20performed%20by,equipped%20with%20HRV%20analysis%20modules. 

• Ferreira S, Rodrigues M A, Mateus C, Rodrigues P P, Rocha N B. Interventions Based on Biofeedback Systems to Improve Workers’ Psychological Well-Being, Mental Health, and Safety: Systematic Literature Review. Journal of Medical Internet Research (2025). DOI: 10.2196/70134. JMIR+2JMIR+2
• Lässing J, Wegener F, Höpker N, Hottenrott K, Gronwald T, Falz R. Heart rate variability response of intensity-matched strength training dependent on body position in females: a pilot randomized crossover study. Scientific Reports (2025). DOI: 10.1038/s41598-025-19817-7. Nature+1
• Książek K, Masarczyk W, Głomb P, Romaszewski M, Buza K, Sekuła P, Cholewa M, Kołodziej K, Gorczyca P, Piegza M. Deep learning approach for automatic assessment of schizophrenia and bipolar disorder in patients using R-R intervals. PLoS Computational Biology (2025). DOI: 10.1371/journal.pcbi.1012983. PLOS+1
• Zilcha-Mano S, Tchizick A, Nof A, Malka M, Oded Y. Clinical breakthroughs or research oversights? The imperative of integrating modalities to differentiate signal from noise. The British Journal of Psychiatry (First View, 2025). DOI: 10.1192/bjp.2025.10321. Cambridge University Press & Assessment
• Dear Media. “7 Lab Tests Every Woman in Her 30s Should Know, According to Dr. Sara Szal.” By Jane LaCroix. September 16, 2025. Dear Media

References for this episode. 

Fred Shaffer's work: https://youtu.be/ajwgwzn2ZUo

Sources for this summary: Vaschillo/Lehrer et al., laboratory demonstration that 0.1-Hz rhythmic skeletal muscle tension increases 0.1-Hz power in heart rate, systolic pressure, and pulse transit time and strengthens HR–BP coupling, consistent with baroreflex resonance; includes with- and without-leg-crossing conditions (N≈37). ResearchGate Shaffer, Moss, & Meehan (2022) randomized study showing that one and six contractions per minute increased multiple HRV metrics versus twelve per minute, with a ~0.10-Hz peak at six per minute. SpringerLink Meehan & Shaffer (2023) within-subjects study showing greater HR, HR max–min, and low-frequency power when adding core contraction and leg-crossing versus wrist-ankle alone at six contractions per minute. SpringerLink Frontiers in Neuroscience review describing the resonance-frequency model and noting that rhythmic skeletal muscle tension, like slow breathing, can stimulate the baroreflex at ~0.1 Hz. Frontiers Clinical and physiological studies on leg-crossing and muscle-tensing maneuvers increasing cardiac output, mean arterial pressure, and cerebral oxygenation during orthostatic stress and vasovagal reactions. Europe PMC+2Physiology Journals+2 Systematic reviews and trials on isometric handgrip training showing blood-pressure reductions with mixed HRV effects, distinct from contraction-based biofeedback. Nature+1

We dive into what these findings mean for clinicians, researchers, and anyone using HRV to track resilience, recovery, or performance.

References

• Cui, Y., Zhang, W., Xu, J., Liu, Y., & Chen, H. (2025). Non-Contact Heart Rate Variability Monitoring with FMCW Radar via a Novel Signal Processing Algorithm. Sensors, 25(17), 5607. Read here

• Zhang, J., Niu, X., Wei, X., Ma, J., & Du, W. (2025). Effects of Induced Physical Fatigue on Heart Rate Variability in Healthy Young Adults. Sensors, 25(17), 5572. Read here

• Pramanik, P. (2025, September 8). Wearable health trackers reveal how accurate your smartwatch really is. News-Medical. Read here

MacDonald, D. M., et al. (2025). Two-week heart rate variability measurements and lung health: A cross-sectional analysis in the ARIC Study. Respiratory Medicine, 234, 108338.

https://www.resmedjournal.com/article/S0954-6111(25)00401-9/abstract

Kamiya, Y., Saita, K., Kaneko, F., Li, J., & Okamura, H. (2025). Association between sense of coherence and phasic heart rate variability under psychosocial stress conditions. Physiology & Behavior, 298, 114969.

https://www.sciencedirect.com/science/article/abs/pii/S0031938425001702?via%3Dihub

European Society of Cardiology. (2025). How wearables are transforming remote monitoring of cardiovascular diseases. ESC 365 session page, ESC Congress 2025. Retrieved September 2025 from

https://esc365.escardio.org/esc-congress/sessions/13953?

Zhang, S., Niu, X., Ma, J., Wei, X., Zhang, J., & Du, W. (2025). Effects of sleep deprivation on heart rate variability: A systematic review and meta-analysis. Frontiers in Neurology, 16, 1556784. 

https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2025.1556784/full

Menuet, C., Ben-Tal, A., Linossier, A., Allen, A. M., Machado, B. H., Moraes, D. J. A., … Gourine, A. V. (2025). Redefining respiratory sinus arrhythmia as respiratory heart rate variability: An international expert recommendation for terminological clarity. Nature Reviews Cardiology. 

https://www.nature.com/articles/s41569-025-01160-z

1. Wu, Y-R., Su, W-S., Lin, K-D., & Lin, I-M. (2025). Effect of Heart Rate Variability Biofeedback on Cardiac Autonomic Activation and Diabetes Self-Care in Patients with Type II Diabetes Mellitus. Applied Psychophysiology and Biofeedback, 50(3), 315–327. https://link.springer.com/article/10.1007/s10484-024-09666-x
   
   
2. Kula, Y., Iversen, Z., Levine, A.D., & Gidron, Y. (2025). Does Vagal Nerve Activity Predict Performance in a Naval Commando Selection Test? Applied Psychophysiology and Biofeedback, 50(3), 349–357. https://link.springer.com/article/10.1007/s10484-025-09702-4
   
   
3. Addleman, J.S., Lackey, N.S., Tobin, M.A., et al. (2025). Heart Rate Variability Applications in Medical Specialties: A Narrative Review. Applied Psychophysiology and Biofeedback, 50(3), 359–381. https://link.springer.com/article/10.1007/s10484-025-09708-y
   
   
4. Wu, D-W., Yang, P-C., & Lin, I-M. (2025). Effects of Heart Rate Variability Biofeedback on Pulmonary Indicators and HRV Indices Among Patients with COPD. Applied Psychophysiology and Biofeedback, 50(3), 383–394. https://link.springer.com/article/10.1007/s10484-024-09664-z
   
   
5. Yang, P-C., Lin, I-M., & Wu, D-W. (2025). Effects of Heart Rate Variability Biofeedback on Enhancing Self-Efficacy, Quality of Life, and Six-Minute Walk Test in Patients with COPD. Applied Psychophysiology and Biofeedback, 50(3), 403–416. https://link.springer.com/article/10.1007/s10484-025-09689-y
6. Bufo, M.R., Guidotti, M., Lemaire, M., et al. (2025). Autonomic Disequilibrium at Rest in Autistic Children and Adults. Applied Psychophysiology and Biofeedback, 50(3), 465–480.
   https://link.springer.com/article/10.1007/s10484-025-09696-z
7. Chakraborty, H., Vinay, A.V., Sindhu, R., & Sinha, R. (2025). Exploring the Immediate Effects of Nadi Shuddhi Pranayama on Heart Rate Variability Among Young Adults. Applied Psychophysiology and Biofeedback, 50(3), 525–533. https://link.springer.com/article/10.1007/s10484-025-09710-4
8. Liu, Z., Zheng, S., Wang, H., & Wang, H. (2025). Acute Effects of Resonance Breathing on Skin Sympathetic Nerve Activity and Heart Rate Variability in Healthy Adults. Applied Psychophysiology and Biofeedback, 50(3), 535–545. https://link.springer.com/article/10.1007/s10484-025-09711-3
9. Dewig, H.G., Cohen, J.N., Renaghan, E.J., et al. (2024). Are Wearable Photoplethysmogram-Based Heart Rate Variability Measures Equivalent to Electrocardiogram? A Simulation Study. Sports Medicine, 54(12), 2927–2934. https://link.springer.com/article/10.1007/s40279-024-02066-5
   
   
10. Reynolds, G. (2025, August 19). This often-ignored smartwatch health metric can help you manage stress. The Washington Post – Well+Being. https://www.washingtonpost.com/wellness/2025/08/19/heart-rate-variability-stress-longevity/
    
    
11. Filchenko, I., et al. (2025, June). Heart rate variability during sleep as an early warning sign of future stroke, depression, and cognitive decline. EAN Congress 2025 presentation, reported by News-Medical.

https://www.news-medical.net/news/20250620/Study-links-sleep-heart-rate-variability-to-stroke-and-depression-risk.aspx#:~:text=Study%20links%20sleep%20heart%20rate,to%20stroke%20and%20depression%20risk

http://recoveryandbalance.com/

Stephanie uses visual demonstrations throughout this episode. You can see these visuals on our YouTube Channel.  https://youtu.be/gj6DHPSWEVY

Erik Peper’s teaching and research focuses on self-healing strategies, illness prevention, the effects of posture and respiration, and how to use biofeedback and wearable devices. Each year he mentors undergraduate student researchers to create and complete studies that are presented at scientific meetings. He is an international authority on biofeedback and self-regulation and author of scientific articles and books such as Make Health Happen, Fighting Cancer-A Nontoxic Approach to Treatment, and Biofeedback Mastery. His most recent co-authored book is, TechStress: How Technology is Hijacking Our Lives, Strategies for Coping, and Pragmatic Ergonomics.  He publishes the blog, The Peper Perspective-ideas on illness, health and well-being (peperperspective.com). In 2013 was received the Biofeedback Distinguished Scientist Award in recognition of outstanding career & scientific contributions from the Association for Applied Psychophysiology.

Email: epeper@sfsu.edu

Web: https://rpt.sfsu.edu/ihhs

Blog: www.peperperspective.com

Web: www.biofeedbackhealth.org

Josh is a 1st-year student studying clinical psychology at Brigham Young University. He is interested in combining psychotherapy with biofeedback to improve mental health treatment outcomes. He works under the mentorship of Dr. Patrick Steffen. Josh is also a father of two little boys and loves spending time with his family.

Here is a link to the presentation slides for Josh's thesis, including data and graphs for the data: https://docs.google.com/presentation/d/1djNhRAn7avAgO3ZNwFV3d4VjvZJBOIsJ/edit?usp=sharing&ouid=115393129857853066622&rtpof=true&sd=true

Psychophysiology Resilience Training (PRT) is a 12-session, mindfulness-based biofeedback treatment protocol developed by Drs. Nate Ewigman & Aliyah Snyder. The treatment is applicable to a wide range of conditions and concerns that impact stress management and recovery by way of the Autonomic Nervous System. Some examples include traumatic brain injury, long COVID, migraine, chronic pain, anxiety, and depression. In the first part of treatment, the client receives a stress profile which is a comprehensive psychophysiological assessment with individualized feedback and then learns evidence-based skills of psychophysiological stress recovery. After these skills are mastered and practiced regularly, the client then learns about their mind-body connection and how it relates to their concerns and/or symptoms, how to improve their healthy body awareness, skillful ways to deal with emotions and thoughts, and how to use these techniques to recover from and prevent stress from becoming chronic. Finally, the client receives tailored feedback on their progress. Currently, this treatment is still being tested and is currently only available in person in private clinics in Los Angeles and the San Francisco Bay Area.

Nate Ewigman: drnateewigman@gmail.com 

Aliyah Snyder: aliyahsnyderphd@gmail.com

Dr. Christine Sanchez specializes in providing mental skills training and executive coaching to high level performers and teams. Her diverse portfolio of clients includes elite military service members, first responders, executives, professional athletes, and other performers who desire to unlock their true potential. She is passionate about being an “aid to navigation” in assisting clients to return home to their authentic self and purpose.

Dr. Sanchez is best known for her work targeting mindful performance under pressure, productive failures, and well-being optimization. She routinely integrates Heart Rate Variability Biofeedback and capnography training for facilitating optimal performance in high stress scenarios. Restorative practices for deliberate recovery is a popular topic she works with clients on, integrating breathwork, nature based wisdom, mindfulness, meaningful social connection, and movement.

 Dr. Sanchez earned her PhD in Sport and Performance Psychology from Florida State University, and currently holds the following certifications: Board Certified in Biofeedback (BCB), Certified Mental Performance Consultant (CMPC), Certified Breathing Behavioral Analyst (CBBA), and ICF Associate Certified Coach (in progress). She resides in Virginia Beach, VA where she soaks up all the water time she can get paddling, surfing, and swimming.

Web:        www.measurableresilience.com

Fredric Shaffer, PhD, BCB-HRV is a biological psychologist and professor of Psychology and former Department Chair at Truman State University, where he has taught since 1975 and has served as Director of Truman’s Center for Applied Psychophysiology since 1977. In 2008, he received the Walker and Doris Allen Fellowship for Faculty Excellence. In 2013, he received the Truman State University Outstanding Research Mentor of the Year award. Dr. Shaffer was the principal co-editor of Evidence-Based Practice in Biofeedback and Neurofeedback (3rd ed.) and authored 12 of its chapters. He was a co-editor with Donald Moss of Foundations of Heart Rate Variability Biofeedback: A Book of Readings. He co-authored with Mark S. Schwartz a chapter on entering the field and assuring competence in Biofeedback: A Practitioner's Guide (4th ed.). He co-authored with Donald Moss, a chapter on biofeedback in the Textbook of Complementary and Alternative Medicine (2nd ed.). He co-authored with Rollin McCraty and Christopher Zerr, the Frontiers in Psychology review article "A healthy heart is not a metronome: An integrative review of the heart's anatomy and heart rate variability." He co-authored with Jack Ginsberg, the Frontiers in Public Health review article “An Overview of heart rate variability (HRV) metrics and norms.” He is a contributing editor for the journal Applied Psychophysiology and Biofeedback. His current research focuses on techniques to increase heart rate variability. Dr. Shaffer is a BCIA Senior Diplomate in Biofeedback. Dr. Shaffer is the Past-Chair of the Biofeedback Certification International Alliance (BCIA), director of its Biofeedback and HRV Biofeedback Task Forces, and member of its Neurofeedback Task Force, and Treasurer for the Association for Applied Psychophysiology and Biofeedback (AAPB).  https://www.truman.edu/faculty-staff/fshaffer/

Fredric Shaffer, PhD, BCB-HRV is a biological psychologist and professor of Psychology and former Department Chair at Truman State University, where he has taught since 1975 and has served as Director of Truman’s Center for Applied Psychophysiology since 1977. In 2008, he received the Walker and Doris Allen Fellowship for Faculty Excellence. In 2013, he received the Truman State University Outstanding Research Mentor of the Year award. Dr. Shaffer was the principal co-editor of Evidence-Based Practice in Biofeedback and Neurofeedback (3rd ed.) and authored 12 of its chapters. He was a co-editor with Donald Moss of Foundations of Heart Rate Variability Biofeedback: A Book of Readings. He co-authored with Mark S. Schwartz a chapter on entering the field and assuring competence in Biofeedback: A Practitioner's Guide (4th ed.). He co-authored with Donald Moss, a chapter on biofeedback in the Textbook of Complementary and Alternative Medicine (2nd ed.). He co-authored with Rollin McCraty and Christopher Zerr, the Frontiers in Psychology review article "A healthy heart is not a metronome: An integrative review of the heart's anatomy and heart rate variability." He co-authored with Jack Ginsberg, the Frontiers in Public Health review article “An Overview of heart rate variability (HRV) metrics and norms.” He is a contributing editor for the journal Applied Psychophysiology and Biofeedback. His current research focuses on techniques to increase heart rate variability. Dr. Shaffer is a BCIA Senior Diplomate in Biofeedback. Dr. Shaffer is the Past-Chair of the Biofeedback Certification International Alliance (BCIA), director of its Biofeedback and HRV Biofeedback Task Forces, and member of its Neurofeedback Task Force, and Treasurer for the Association for Applied Psychophysiology and Biofeedback (AAPB).  https://www.truman.edu/faculty-staff/fshaffer/

Deb obtained her master’s degree in social work at Columbia University and her medical training at Brown University and UCSF. As both a social worker and a physician, she has worked with highly marginalized communities, including homeless persons, drug users, psychiatric patients, and incarcerated and recently released individuals. Deb is very interested in how research can inform and assist with community-based clinical work. HIV prevention is one of her personal and professional passions.

https://cfar.ucsf.edu/people/deborah-borne

Read Janell's paper: https://www.tandfonline.com/doi/full/10.1080/00223891.2024.2445706#abstract

Learn more about Optimal HRV https://www.optimalhrv.com

Learn more about Inna Khazan https://www.innakhazan.com/

http://harveyhealthperspectives.com/

On this episode, Greg shares his expertise on how to use Heart Rate Variability data for better health outcomes. He explains what HRV is, how it works in the body, and how we can use it to measure our physical and mental well-being. He also talks about why he developed HealthQb and how the company is helping people take control of their health through technology. 

 Tune in to hear all about Heart Rate Variability and learn more about HealthQb Technologies Inc with Greg!

Dr. Aseem Desai, the “Heart-Mind Doc,” is a Stanford-trained cardiologist, author, and speaker,
known for his expertise in heart rhythm disorders and the connection between heart health and
mental well-being. As Co-Director of Mission Heritage Heart Rhythm Specialists and author of
the Mindful Beats blog on Psychology Today, he offers practical insights on living a balanced life
by blending science with personal experience. Inspired by his father’s heart attack at age 3 and
subsequent cardiac arrest, Dr. Desai dedicated his career to preventing and treating sudden death.
Drawing from his own mental health challenges and the struggles he has seen in his patients,
colleagues, and healthcare workers, he integrates heart and mind health in his work. He is the
best-selling author of Restart Your Heart: The Playbook for Thriving with AFib and the
forthcoming Restart Your Mind: The Playbook for Finding Balance in a Sometimes Chaotic
World, where he introduces the M.I.N.D. and R.E.S.T.A.R.T. Frameworks for mental and
emotional balance. His work has been featured in Forbes, Men’s Health, Healthline, and Thrive
Global. Dr. Desai's "5 Life Rhythms" approach—physical, mental, emotional, social, and
spiritual balance—is featured on his website. He enjoys yoga, mindfulness, and playing guitar in
his personal life. Learn more at draseemdesai.com.

Website:https://www.biosourcesoftware.com

Email:fred@biosourcesoftware.com

Bio: Fredric Bruce Shaffer, PhD, BCB, BCB-HRV, is a professor of psychology at Truman State University and an adjunct faculty member at Saybrook University. He earned his PhD and MS in Psychology from Oklahoma State University and a BA in Psychology and Political Science from Claremont Men’s College. Dr. Shaffer is a BCIA Senior Fellow in Biofeedback and holds certification in HRV Biofeedback. He has served as President, Treasurer, and Program Chair of AAPB, as well as Treasurer, Chair, and Board Member of BCIA. Additionally, he co-edits "Evidence-Based Practice in Biofeedback and Neurofeedback". Dr. Shaffer has been honored as a Distinguished Scientist and an Honorary Fellow by AAPB and received the Outstanding Research Mentor award from Truman State University. He has taught a range of courses including Clinical Psychology, Crisis Intervention, Experimental Psychology, HRV Biofeedback, and Physiological Psychology. Dr. Shaffer has presented extensively on HRV biofeedback and neuroscience at professional conferences and webinars. He can be contacted at fredricshaffer@gmail.com or 660-349-9522.

- David’s Baroreflex Sketch https://imgur.com/Jrb2Anj
- Supplementary images: https://imgur.com/a/ZLoB8FB
- Video of David demonstrating cardiovagal and neurovascular resonance frequencies with Pranawave software: https://www.youtube.com/watch?v=WRS5-rBw-0w
- Vaschillo et al. (2002) on Baroreflex Resonance Loops: https://www.researchgate.net/publication/11368894
- Atasoy et al. (2016) on Brain Connectome Harmonics: https://doi.org/10.1038/ncomms10340
- Mather & Thayer (2018) "How heart rate variability affects emotion regulation brain networks": https://doi.org/10.1016%2Fj.cobeha.2017.12.017

Order your copy: Integrating Psychotherapy and Psychophysiology: Theory, Assessment, and Practice