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MEDICAL DISCLAIMER The information in this podcast is for educational and informational purposes only and is not intended to diagnose, treat, cure, or prevent any medical condition. Please consult with a qualified healthcare provider before making any changes to your health regimen, training program, or clinical practice. Heart rate variability is a powerful and scientifically validated tool for understanding autonomic nervous system function, but it is one piece of a much larger picture, and context always matters. Nothing shared in this podcast should be taken as personalized medical advice, and individual responses to interventions vary enormously. Always work with qualified professionals when making decisions about your health. This week on This Week in HRV, seven studies examine the second generation of HRV science—asking not just whether HRV matters but who it matters for, under what conditions, and whether our analytical tools reveal biology or only statistical patterns. The episode covers sex differences in the brain-heart axis, the autonomic effects of touch after social exclusion in adolescents, the physiology of co-sleeping with pets and children, ear-based vagus nerve stimulation and baroreflex sensitivity, an open-source framework for brain-heart coupling during sleep, physiological responses to urban streetscapes, and a methodological challenge to interpreting machine-learning feature importance in HRV research. 1. Sex Differences in the Brain-Heart Axis and Cognitive Function: Insights from Heart Rate Variability PUBLICATION: Sex- and Gender-Specific Biomedicine AUTHORS: So Yi Yoon, Hee Sang Yang, Maithreyee Devi, Jihye Lee, Nayoung Yoon, Eun Hwa Lee, Hyang Woon Lee KEY FINDING: A synthesis of fifteen years of neuroimaging and autonomic research found that women consistently show stronger limbic and interoceptive brain activation (amygdala, insula) during HRV-regulating tasks, while men show stronger prefrontal activation, suggesting the brain-heart axis is regulated through partially different neural pathways by sex. SIGNIFICANCE: HRV normative ranges and research findings derived from mixed-sex samples may not apply equally to men and women; sex should be treated as a biological variable of interest rather than a covariate to control, with implications for normative databases and individual clinical interpretation. Read the full study: https://doi.org/10.65400/SGBM.2026.1.3.231 2. Touch promotes emotional and autonomic recovery following virtual social exclusion in early adolescents PUBLICATION: Frontiers in Psychology AUTHORS: Letizia Della Longa, Irene Guglielminetti, Irene Valori, Francesco Rizzi, Gustavo Marfia, Teresa Farroni KEY FINDING: In sixty-seven early adolescents randomized after virtual social exclusion (VR Cyberball), a brief forearm stroking touch produced significantly better autonomic recovery—lower heart rate, more favorable parasympathetic balance, improved mood—compared to a neutral auditory control, with exploratory evidence suggesting stronger benefits for lonelier participants. SIGNIFICANCE: Affective touch activates C-tactile afferent pathways with measurable autonomic effects; appropriate physical contact may serve as a meaningful regulatory tool for young people experiencing social stress. Read the full study: https://doi.org/10.3389/fpsyg.2026.1981624 3. Who's Been Sleeping in My Bedroom? Associations Between Co-Sleeping with Dogs, Cats, or Children and Sleep and Cardiorespiratory Physiology Among WHOOP Users PUBLIC...

MEDICAL DISCLAIMER The information in this podcast is for educational and informational purposes only and is not intended to diagnose, treat, cure, or prevent any medical condition. Please consult with a qualified healthcare provider before making any changes to your health regimen, training program, or clinical practice. Heart rate variability is a powerful and scientifically validated tool for understanding autonomic nervous system function, but it is one piece of a much larger picture, and context always matters. Nothing shared in this podcast should be taken as personalized medical advice, and individual responses to interventions vary enormously. Always work with qualified professionals when making decisions about your health. This week on This Week in HRV, we explore four studies connecting HRV to cognitive performance and autonomic regulation: a brief app-guided breathing intervention for stressed students, dose-dependent effects of classroom crowding on the autonomic nervous system, consumer biosensor validation for detecting mental workload, and the task-specific effects of acute aerobic exercise on working memory and HRV. 1. Effects of a brief resonance frequency breathing intervention on heart rate variability and perceived stress in postgraduate students: a pilot and feasibility study PUBLICATION: Frontiers in Psychology AUTHORS: Alessandro Spizzirri, Neil Buchanan KEY FINDING: In a randomized pilot with twelve postgraduate students, ten minutes of daily app-guided resonance frequency breathing over three weeks produced statistically significant increases in SDNN (weeks two and three) and RMSSD (week three) versus a waitlist control, alongside a ten-and-a-half-point divergence in perceived stress scores (breathing group declined six points; control rose four-and-a-half points), though the between-group stress difference did not reach statistical significance in this small sample. SIGNIFICANCE: Demonstrates that app-based resonance frequency breathing without biofeedback can produce genuine autonomic training effects in a stressed, real-world population, lowering barriers to access compared to clinical biofeedback protocols. Read the full study: https://doi.org/10.3389/fpsyg.2026.1787922 2. Dose-dependent cardiac autonomic dysregulation under classroom crowding: heart rate variability analysis and machine learning classification PUBLICATION: Journal of Physiological Anthropology AUTHORS: Mohamed Naeem KEY FINDING: In thirty university students attending identical lectures in rooms of thirty, sixty, and one hundred students, all twenty-five HRV parameters changed significantly as crowding increased; pNN50 fell fifty-two percent, high-frequency power fell fifty-one percent, and RMSSD fell thirty-two percent in the most crowded condition, while NASA-TLX workload scores rose seventy-four percent. A machine learning classifier identified crowding level with ninety-two-point-two percent accuracy across all three conditions and ninety-seven-point-two percent accuracy for any pairwise comparison, with autonomic effects persisting throughout each thirty-minute session without habituation. SIGNIFICANCE: Provides the first dose-response evidence that classroom crowding suppresses parasympathetic tone at a scale detectable by machine learning, with implications for educational space design and shared workspaces. Read the full study: https://doi.org/10.1186/s40101-026-00451-9 3. Sensitivity of a Consumer-Grade Electroencephalography Headset and Portable Heart Rate Variability Monitor f...

Dr. Erik Peper joins Matt Bennett on the Heart Rate Variability Podcast for a wide-ranging conversation about cancer, genetics, lifestyle, autonomic regulation, and the role of biofeedback in understanding health. Drawing on decades of research in biofeedback and self-regulation, and on themes from his book Cancer Reconsidered, Dr. Peper explores why genetic predisposition does not always determine health outcomes and how factors such as environment, nutrition, stress, breathing, immune function, social connection, and behavior may influence our physiology. The conversation covers epigenetics, endocrine-disrupting chemicals, ultra-processed foods, glucose metabolism, micronutrients, psychological safety, breathing mechanics, and Dr. Peper's own experience with melanoma. Matt and Dr. Peper also discuss heart rate variability and autonomic health, noting an important limitation: direct research linking HRV specifically to cancer remains limited. Their conversation highlights where established research ends and where emerging hypotheses and clinical observations begin. This episode offers a broader perspective on how the nervous system, environment, behavior, and health may interact—and why understanding those relationships requires looking beyond genetics alone. Learn more: https://www.optimalhrv.com For educational and informational purposes only. This podcast does not constitute medical advice, diagnosis, or treatment.

MEDICAL DISCLAIMER The information in this podcast is for educational and informational purposes only and is not intended to diagnose, treat, cure, or prevent any medical condition. Please consult with a qualified healthcare provider before making any changes to your health regimen, training program, or clinical practice. Heart rate variability is a powerful and scientifically validated tool for understanding autonomic nervous system function, but it is one piece of a much larger picture, and context always matters. Nothing shared in this podcast should be taken as personalized medical advice, and individual responses to interventions vary enormously. Always work with qualified professionals when making decisions about your health. This week on This Week in HRV, we explore seven new studies on the relationship between heart rate variability and mental health. The episode covers a landmark registered-report meta-analysis mapping HRV across the full spectrum of psychological conditions, a structured biofeedback-based stress resilience training program, a cross-sectional study on cyberchondria and HRV in university students, a novel smartwatch monitoring study in children undergoing behavioral therapy, a virtual nature pilot in adults with disabilities, a real-world randomized trial of just-in-time slow-paced breathing for anxiety, and a virtual reality mindfulness program that improved both HRV and emotional skills in elementary school children. 1. A Meta-Analysis of Heart Rate Variability and Psychopathology: An Investigation Guided by the Hierarchical Taxonomy of Psychopathology Framework PUBLICATION: Journal of Psychopathology and Clinical Science AUTHORS: Tam Pham, Carly J. Johnco, Ana Neves, Wilson P. H. Lim, Gladys J. Heng, Rachel Ygnacio, Miriam K. Forbes KEY FINDING: This pre-registered meta-analysis of 430 studies (732 effect sizes, 62,264 participants) found that lower resting HRV was significantly associated with most major mental health conditions — including depression, anxiety, PTSD, bipolar disorder, schizophrenia, autism, and borderline personality disorder — but not with OCD, social anxiety, or ADHD. Associations were stronger in more severely affected samples, and psychotic conditions showed the largest effects. SIGNIFICANCE: HRV appears to function as a transdiagnostic marker of regulatory capacity rather than a fingerprint of any single disorder. For HRV practitioners, this confirms that consistently low resting HRV is a meaningful signal of dysregulation severity across a wide range of mental health presentations — not just anxiety or depression. Read the full study: https://psycnet.apa.org/fulltext/2028-01747-001.html 2. Biofeedback-Enhanced Stress Resilience Training: Transforming Stress into Positive Energy, Positive Mental Focus, and Positive Mood PUBLICATION: Biofeedback (Special Issue) AUTHORS: Patrick Steffen KEY FINDING: This paper describes a three-phase clinical program — BE-SRT — that combines HRV biofeedback with acceptance and commitment therapy, cognitive behavioral therapy, and interpersonal therapy to help clients transform chronic stress into a productive resource rather than simply reducing it. SIGNIFICANCE: BE-SRT provides practitioners with a structured framework for integrating HRV biofeedback into psychotherapy across three domains: physiological self-regulation, values-based focus, and resilience capacity (body, mind, and relationships). It bridges a gap between biofeedback and psychotherapy that often leaves both disciplines underutilized in practice. Read the full study:

MEDICAL DISCLAIMER The information in this podcast is for educational and informational purposes only and is not intended to diagnose, treat, cure, or prevent any medical condition. Please consult with a qualified healthcare provider before making any changes to your health regimen, training program, or clinical practice. Heart rate variability is a powerful and scientifically validated tool for understanding autonomic nervous system function, but it is one piece of a much larger picture, and context always matters. Nothing shared in this podcast should be taken as personalized medical advice, and individual responses to interventions vary enormously. Always work with qualified professionals when making decisions about your health. This week on This Week in HRV, eight studies covering the reach of the autonomic nervous system across a wide range of health contexts — pulse rate variability and mortality in a large Japanese cohort, autonomic dysregulation in stable COPD, cardiac autonomic dysfunction in childhood obesity, HRV-based monitoring of caesarean recovery, anxiety and depression in women with PCOS, periodontal disease and autonomic imbalance, handgrip strength and cardiac autonomic neuropathy in type 2 diabetes, and nonlinear HRV methods distinguishing long COVID from depressive disorders in youth. 1. Pulse Rate Variability and All-Cause Mortality Risk in the General Japanese Population PUBLICATION: Circulation Reports AUTHORS: Isao Saito, Koutatsu Maruyama, Tadahiro Kato, Yayoi Funakoshi, Yasunori Takata, Kiyohide Tomooka, Ryoichi Kawamura, Haruhiko Osawa, Takeshi Tanigawa KEY FINDING: In a prospective cohort of 5,943 Japanese adults followed a median 12.4 years (437 deaths), the lowest SDNN quartile had a hazard ratio of 1.39 for all-cause mortality after adjusting for resting heart rate. Low HF power was also independently associated with mortality. RMSSD and pNN50 lost significance once resting HR was included. SIGNIFICANCE: Large population-level evidence that photoplethysmography-derived PRV carries a mortality signal over more than a decade, supporting the prognostic relevance of consumer wearable HRV signals. Read the full study: https://doi.org/10.1253/circrep.CR-25-0193 2. Correlation of Heart Rate Variability as a Measure of Autonomic Dysregulation in Stable Chronic Obstructive Pulmonary Disease PUBLICATION: Cureus AUTHORS: Dinakaran Umashankar, Karthikeyan Ramaraju, Anupama Murthy, Nagashree R KEY FINDING: In 47 stable COPD patients, HRV did not correlate with BODE index, GOLD severity, or COPD phenotype. Longer disease duration correlated with lower RMSSD (r = −0.324) and pNN50 (r = −0.332). Higher SGRQ impact score correlated with lower SDNN (r = −0.294). SIGNIFICANCE: Autonomic erosion in COPD tracks cumulative disease burden and quality of life rather than standard severity classifications, suggesting HRV adds a complementary longitudinal dimension to COPD monitoring. Read the full study: https://doi.org/10.7759/cureus.107493 3. Cardiac Autonomic Dysfunction in Children and Adolescents with Obesity: A Systematic Review and Meta-Analysis PUBLICATION: Revista Paulista de Pediatria AUTHORS: Thales da Fonseca Dornelles, Júlia Lima Barrozo KEY FINDING: Meta-analysis of 18 studies (1,590 children) found excess-weight youth had lower RMSSD (SMD −1.00), lower pNN50 (SMD −0.48), and higher LF/HF ratio (SMD 0.70) compared to normal-weight peers. pNN50 showed the most consistent signal (low hetero...

Can heart rate variability help clinicians better understand—and eventually anticipate—the challenges people face during recovery from substance use disorder? In this episode of the Heart Rate Variability Podcast, host Matt Bennett speaks with Dr. J. Gregory Hobelmann, Dr. Wendy Insalaco, and Dr. Andrew Huhn about their research on physiological and mental health changes during residential substance-use disorder treatment. Their study paired wearable measurements of heart rate variability (HRV) and resting heart rate with self-reported assessments of stress, anxiety, and depression. Although participants generally demonstrated favorable changes during treatment, their individual trajectories varied widely. For some people, physiological and self-reported improvements aligned; for others, the two told different stories. The conversation explores why this variability matters, how objective biomarkers may complement—not replace—traditional clinical assessments, and how wearable data could eventually support more individualized care, timely check-ins, and relapse-prevention efforts. Topics discussed include: What a typical 28-day residential treatment experience involves Why substance-use treatment outcomes have traditionally relied heavily on self-report How WHOOP wearables were used to monitor HRV and resting heart rate The relationship between HRV, stress, anxiety, and depression Why physiological recovery and perceived wellness do not always move together State-versus-trait differences in anxiety and autonomic functioning The importance of sleep and healthy cortisol patterns during recovery Using biometric changes as prompts for supportive clinical conversations The risks of overconfidence and overreliance on wearable data The potential for personalized treatment plans and just-in-time interventions How academic and residential-treatment partnerships can advance precision medicine About the guests: Dr. J. Gregory Hobelmann, MD, MPH, is an addiction psychiatrist and Co-CEO and President of Ashley Addiction Treatment in Havre de Grace, Maryland. Wendy Insalaco, PhD, LCADC, LCPC, is an addiction psychologist and researcher who serves as Director of Quality Outcomes and Model of Care at Ashley Addiction Treatment. Andrew S. Huhn, MBA, PhD, is an Associate Professor of Psychiatry and Behavioral Sciences at the Johns Hopkins University School of Medicine. His research examines opioid use disorder, relapse risk, sleep, stress, mood, wearable technology, and treatment outcomes. Resources: Read the study: https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2026.1755153/full Learn about Ashley Addiction Treatment: https://www.ashleytreatment.org/ Learn more about Dr. Andrew Huhn: https://profiles.hopkinsmedicine.org/provider/andrew-stephen-huhn/2777487 Explore Optimal HRV: https://www.optimalhrv.com/ The Heart Rate Variability Podcast is produced by Optimal LLC and Optimal HRV. This podcast is provided for informational purposes only and is not medical advice. Consult a qualified healthcare professional before applying any strategies discussed in this episode.

MEDICAL DISCLAIMER The information in this podcast is for educational and informational purposes only and is not intended to diagnose, treat, cure, or prevent any medical condition. Please consult with a qualified healthcare provider before making any changes to your health regimen, training program, or clinical practice. Heart rate variability is a powerful and scientifically validated tool for understanding autonomic nervous system function, but it is one piece of a much larger picture, and context always matters. Nothing shared in this podcast should be taken as personalized medical advice, and individual responses to interventions vary enormously. Always work with qualified professionals when making decisions about your health. This week on This Week in HRV, we explore the relationship between HRV and human performance across four distinct domains — golf putting, sustained cognitive work, drowsy driving, and competitive wrestling. Together, these studies reveal how the autonomic nervous system shapes and reflects our capacity to perform under pressure, sustain attention, stay alert, and adapt to training stress. 1. Exploring Attentional Mechanisms of Strategic Self-Talk Through Heart-Rate Variability in a Golf-Putting Task Among Novices PUBLICATION: Behavioral Sciences AUTHORS: Emmanouil Tzormpatzakis, Theodoros Proskinitopoulos, Orestis Panoulas, Evangelos Galanis, Evgenia Nikolakopoulou, Nikos Comoutos, Yannis Theodorakis, Antonis Hatzigeorgiadis KEY FINDING: Novice golfers who underwent personalized self-talk training showed progressively higher parasympathetic activation (RMSSD) in later stages of a putting task at the final assessment — a pattern not seen at baseline or in the control group — alongside significantly better putting performance. SIGNIFICANCE: This study provides preliminary physiological evidence that psychological skills training can shift autonomic regulation toward more efficient, automatic processing during motor performance, opening a new direction for understanding how mental skills work at the level of the nervous system. Read the full study: https://doi.org/10.3390/bs16081347 2. Exploratory Temporal Dynamics of Heart-Rate Variability During a Prolonged Two-Back Task Under Nap-Deprivation Conditions PUBLICATION: Sensors  AUTHORS: Di Meng, Luyao Yu, Tianjiao Min, Jing Zhang, Liufeng Zhu, Hengcong Gong, Yifei Feng, Ying He KEY FINDING: A fiber-optic seat cushion (ballistocardiogram) captured HRV continuously during 60 minutes of demanding cognitive work under nap-deprivation conditions. While mental fatigue was large and unambiguous by self-report and reaction time, no HRV feature survived false discovery rate correction at the group level — and individual HRV trajectories varied dramatically across participants. SIGNIFICANCE: The null group-level result and striking individual heterogeneity together suggest that HRV-based cognitive fatigue monitoring may require personalized calibration rather than universal group-level algorithms, a critical insight for anyone building real-world fatigue detection systems. Read the full study: https://doi.org/10.3390/s26196099 3. Tracking Vigilance While Driving: Pilot Study of Heart Rate Variability Classification Under a Controlled Sleep-Deprivation Protocol PUBLICATION: Sensors AUTHORS: James Elber Duverger, Eli Moser, Philippe Boudreau, Marie Claude Ouimet, Diane B. Boivin, Alireza Saidi KEY FINDING: Twelve healthy adults underwent a 30-hour sleep-deprivation protocol with driving simul...

Medical Disclaimer: The information shared on This Week in HRV is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before making changes to your health routine. This week on This Week in Heart Rate Variability, we cover six studies that together sketch the future of HRV science. Each one points in a distinct direction: a new metric for measuring rhythm organization across a large psychiatric population, a systematic content audit of consumer HRV apps, a rigorous benchmark of five noninvasive sensor technologies measured simultaneously in the same subjects, a new mathematical framework that challenges the stationarity assumption underlying conventional HRV analysis, a nonlinear dynamical study of group physiological coordination using attractor reconstruction and neural network clustering, and a deep learning system that extracts HRV from facial video alone to detect driver drowsiness at nearly ninety-five percent accuracy. What unites these studies is not a single topic but a shared direction: the field is expanding its metrics, scrutinizing its tools, rethinking its assumptions, and reaching toward applications that would have seemed impractical not long ago. 1. Heart rate fragmentation in psychiatry: across age stages and association with conventional heart rate variability PUBLICATION: Psychiatry Research: Neuroimaging AUTHORS: XinFan Zhang, AiMei Ye, Min Su, Hao Chai, YanYan Wei, YiYi Yang, YuXuan Xiong, Yin Cui, Dan Zhang, Xiong Jiao, HuiRu Cui, LiHua Xu, XiaoChen Tang, HaiChun Liu, MingLiang Ju, LingYun Zeng, ChunBo Li, LiYing Huang, Jin Gao, JiJun Wang, and TianHong Zhang KEY FINDING: Researchers analyzed resting three-minute electrocardiograms from 3,813 patients with schizophrenia, depressive disorder, anxiety disorder, or sleep disorder, ranging in age from 10 to 80 years, treated at the Shanghai Mental Health Center. The study derived both heart rate fragmentation indices—specifically the percentage of inflection points (PIP) and the related percentage of alternating segments (PAS)—alongside conventional HRV measures including RMSSD, SDNN, low-frequency power, and high-frequency power. Heart rate fragmentation increased systematically across age groups, while every conventional HRV index declined. That divergence is the central finding: aging appears to produce both less variability and less organized variability, and these are not the same thing. Partial Spearman correlations and multivariable linear regression confirmed that PIP retained independent associations with all conventional HRV metrics, even after adjusting for available covariates, with the strongest association observed for high-frequency power. Sex differences in fragmentation were confined to adolescence and early adulthood, with males showing higher PIP than females in those life stages, but these differences disappeared by middle and late adulthood. Diagnostic category had a statistically significant main effect on PIP, but the differences between diagnostic groups were modest and did not meaningfully interact with age. SIGNIFICANCE: Heart rate fragmentation asks a different question than conventional HRV metrics. While RMSSD and SDNN measure how much the intervals between heartbeats vary, fragmentation measures how organized that variability is. The consistent independent relationship between PIP and conventional HRV metrics suggests that fragmentation captures something about rhythm organization that amplitude-based measures do not fully account for. Because fragmentation can be computed from the same R-R interval data used in conventional HRV analysis, there is no additional measurement burden when adding it to existing protocols. Read th...

In this episode of the Heart Rate Variability Podcast, Matt Bennett talks with Tony Crescenzo, founder and CEO of Peak Neuro and a former U.S. Marine, about heart rate variability, trauma, resilience, neuroscience, and human performance. Tony explores how prolonged exposure to high-stress environments can affect the autonomic nervous system and why resilience requires a highly individualized approach. He also explains why HRV should be understood in context rather than viewed simply as a score where higher is always better. Matt and Tony discuss the neurological challenges faced by veterans and active-duty service members, the difference between resilience and recovery, somatic approaches to trauma, neuromodulation, and Peak Neuro's approach to combining HRV with brain activity and other physiological measurements. Tony also shares experiences from his Marine Corps career and discusses how they have shaped his current work in neuroscience and human performance. The conversation concludes with a look at the growing role of AI, neuroscience, and cognitive-performance technology in military resilience and the future of human optimization. Learn more: Optimal HRV — https://www.optimalhrv.com Peak Neuro — https://peakneuro.com For educational purposes only. This podcast is not intended as medical advice.

Medical Disclaimer: The information shared on This Week in HRV is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before making changes to your health routine. This week on This Week in Heart Rate Variability, we explore how deeply HRV is woven into the biology of mental health. Five studies examine this connection from very different perspectives: structural changes in the brain, biofeedback training for medical students, resting HRV and psychological distress, early prediction of post-stroke depression, and an AI model designed to anticipate depressive episodes in bipolar disorder. 1. Five weeks of daily HRV biofeedback changes the structural relationship between the amygdala and prefrontal cortex PUBLICATION: International Journal of Psychophysiology AUTHORS: Kalekirstos Alemu, Hyun Joo Yoo, Kaoru Nashiro, Jungwon Min, Padideh Nasseri, Christine Cho, Paul Choi, Shelby L. Bachman, Shai Porat, Shubir Dutt, Julian F. Thayer, and Mara Mather KEY FINDING: Researchers analyzed brain scans from younger and older adults who completed five weeks of daily biofeedback practice. Participants were assigned either to increase heart rate oscillations through slow, resonant breathing or to keep their heart rate relatively steady. In the HRV-enhancing condition, changes in left amygdala volume showed an inverse relationship with changes in the right orbitofrontal cortex—a pattern absent in the comparison condition. Coordinated structural changes were also identified across several prefrontal, motor, sensory, and parietal regions. Both younger and older adults demonstrated similar patterns of structural covariance, although the study’s smaller older-adult sample means the age-related findings should be considered exploratory. SIGNIFICANCE: Previous research has linked higher HRV to stronger functional communication between the amygdala and the prefrontal cortex. This study adds a structural layer to that evidence, suggesting HRV biofeedback may influence the coordinated physical architecture of brain regions responsible for emotional regulation. The findings support the neurovisceral integration model, in which the prefrontal cortex helps regulate amygdala-driven emotional and threat responses. They also provide a possible biological mechanism for the use of HRV biofeedback alongside established treatments for anxiety, depression, and post-traumatic stress disorder. Read the full study 2. HRV biofeedback produces large reductions in stress, anxiety, and depression among medical students PUBLICATION: Physiological Reports AUTHORS: Gabriela Panayotova and Margarita Velikova KEY FINDING: Forty-seven international medical students were followed for approximately three months. Students with elevated stress or affective symptoms entered an HRV biofeedback program consisting of two supervised 30-minute sessions per week, while a separate group received no intervention. Within the biofeedback group, perceived stress, anxiety, and depression declined significantly, with large effect sizes ranging from approximately 1.28 to 1.86. Clinically meaningful improvement—defined as a reduction of at least 20%—was reported by: 87.5% of the biofeedback group on the Beck Anxiety Inventory, compared with 34.8% of controls 79.2% on the depression inventory, compared with 34.8% of controls 70.8% on a separate anxiety scale, compared with 8.7% of controls 62.5% on perceived stress, compared with 39.1% of controls During individual sessions, heart rate decreased b...

Medical Disclaimer: The information shared on This Week in HRV is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before making changes to your health routine. This week on This Week in Heart Rate Variability, we explore the theme of Medical — studying HRV across populations dealing with identifiable disease states and clinical questions. From noise exposure in everyday life to smoking, cardiac surgery rehabilitation, rare autoimmune disease, AI-powered sleep staging, and physical activity in chronic lung disease, today's research spans the full clinical spectrum of what HRV can tell us. 1. Every 10 dB increase in environmental noise reduces SDNN by up to 16% over 160 minutes: evidence from the Apple Hearing Study PUBLICATION: Journal of Exposure Science and Environmental Epidemiology (Nature Portfolio) AUTHORS: Xin Zhang, Sung Kyun Park, Lauren M. Smith, and Richard L. Neitzel KEY FINDING: Using wearable-derived SDNN and sound-exposure data from roughly 980–1,180 participants per analysis in the Apple Hearing Study, hierarchical Bayesian distributed-lag models found that each 10 dB increase in environmental noise was associated with an overall SDNN reduction of 6.8% over a short-term (20-minute) window and 16.0% over a long-term (160-minute) window. Headphone sound produced smaller, more consistent reductions of 7.1–7.4% regardless of window length. Reductions were greater in older adults and those with tinnitus. SIGNIFICANCE: This elevates noise — including overnight traffic noise and headphone volume — to the same level of concern as sleep quality, training load, and nutrition in shaping HRV. The data also provides context for unexpectedly low morning HRV readings after noisy nights. Read the full study 2. Ambulatory monitoring reveals what office readings miss: smokers have heart rates nearly 7 bpm higher in daily life — and elevated diastolic blood pressure PUBLICATION: Hypertension Research (Nature Portfolio) AUTHORS: Yuya Akagi, Kimika Arakawa, Atsushi Sakima, Mai Kabayama, Ken Sugimoto, Yuichi Akasaki, Ako Fukami, Satoko Sakata, Hirochika Ryuno, Hiroyuki Kadoya, Toshiya Yamamoto, Hiroko Yoshida, Yoichi Nozato, Taisuke Ueno, Makiko Abe, Hisatomi Arima, Mitsuru Ohishi, Nobuhito Hirawa, Chisa Matsumoto, Shin-Ichiro Miura, Masaki Mogi, Akira Nishiyama, Akihiro Nomura, Takayoshi Ohkubo, Yusuke Ohya, Shigeru Shibata, Yasuharu Tabara, Koichi Yamamoto, and Kazuomi Kario KEY FINDING: This systematic review and meta-analysis of four non-randomized crossover comparative studies (104 participants total) compared ambulatory blood pressure and heart rate within the same current smokers during active smoking versus abstinence periods (1 day to 1 week). Twenty-four-hour diastolic blood pressure was 2.67 mmHg higher during smoking (95% CI 0.72–4.62), and daytime diastolic was 3.17 mmHg higher. Twenty-four-hour heart rate was 6.47 bpm higher during smoking (95% CI 3.98–8.96); daytime 7.19 bpm higher; nighttime 3.58 bpm higher. Systolic blood pressure showed no significant difference between periods. SIGNIFICANCE: This helps explain the long-standing office blood pressure paradox in smokers: they appear similar to non-smokers in clinical readings because they abstain before appointments and are at rest. Ambulatory monitoring reveals the true picture — persistent sympathetic arousal manifesting as chronically elevated heart rate around the clock. For HRV practitioners, this means a smoking patient's measured baseline is not their true autonomic baseline, and it positions HRV tracking as a motivational tool in cessation progra...

In this episode of the Heart Rate Variability Podcast, Matt Bennett sits down with Dr. Patrick K. Porter, PhD, founder of BrainTap®, to explore the connection between brainwave activity, heart rate variability, breathwork, and nervous system regulation. Dr. Porter shares how his interest in brainwave training began at an early age and how decades of work in neuroscience-based performance ultimately led to the development of BrainTap. His background includes extensive work in brainwave entrainment and non-invasive approaches to supporting brain health and human performance. In this conversation, Matt and Dr. Porter discuss how HRV can be used as a practical measure of nervous system activity, why chronic high-stress states may affect cognitive performance and recovery, and how intentional practices can help shift the body toward more regulated states. They also explore: - Brainwave states including beta, alpha, theta, gamma, delta, and SMR - The relationship between HRV, brain activity, and autonomic regulation - Brainwave entrainment compared with neurofeedback - Breathwork practices for different times of the day - Vagal stimulation and simple nervous-system regulation techniques - BrainTap research related to pain, stress, cognitive performance, and recovery - Dr. Porter’s personal routine for supporting brain and nervous system health - How AI may influence the future of personalized brain fitness Dr. Porter also shares his perspective on where brain optimization is headed—from clinics and universities to schools, workplaces, and personalized digital coaching. Whether you’re interested in HRV, neuroscience, biofeedback, breathwork, stress regulation, or improving human performance, this conversation offers a fascinating look at how the brain and autonomic nervous system may work together. Learn more about Optimal HRV: https://www.optimalhrv.com Learn more about BrainTap: https://braintap.com This podcast is for educational purposes only and is not intended to provide medical advice, diagnosis, or treatment.

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history. This week on This Week in Heart Rate Variability, we explore the theme of Performance. Seven studies this week cover urban air pollution, shift work, weighted vests, functional clothing, ergogenic supplementation, elite athlete aging, and real-time exercise intensity classification with DFA-alpha-1. RESEARCH HIGHLIGHTS THIS WEEK 1. Combined mask and headphone use significantly improves HRV during traffic exposure: a randomized crossover RCT PUBLICATION: Journal of Hazardous Materials AUTHORS: Meng, Qi, Wang, and Duan KEY FINDING: In a randomized crossover study, 51 healthy young adults (mean age 20, ~40% female) were exposed to four 2-hour conditions at a high-traffic site in Beijing: no intervention, KN95 mask alone, noise-canceling headphones alone, and both combined. Single interventions did not yield a significant HRV benefit. The combined intervention significantly elevated SDNN (+20.3%), RMSSD (+56.8%), SDSD (+62.0%), pNN50 (+61.1%), LF (+128.6%), and HF (+73.8%) relative to control. It also reduced the myocardial injury marker CK-MB by 27.6% and homocysteine by 79.5%. Females showed greater autonomic benefits than males. SIGNIFICANCE: This finding has real implications for urban athletes and anyone training in polluted environments. Wearing just one intervention (mask or headphones) alone did not provide significant protection, but the combined approach demonstrated robust cardiovascular protection during traffic exposure. Read the full study 2. Night shift workers show elevated heart rate fragmentation independent of traditional HRV changes: MESA Sleep cohort PUBLICATION: Chronobiology International AUTHORS: Multi-Ethnic Study of Atherosclerosis Sleep study cohort analysis KEY FINDING: A cross-sectional analysis of 845 participants (mean age 64, 51% women) compared heart rate variability and heart rate fragmentation (HRF) across shift types. Night and rotating shift workers had significantly higher PAS - the percentage of normal-to-normal intervals in alternation segments - compared to day workers (+11.9%, 95% CI 1.8-22.0). Traditional HRV metrics showed minimal and inconsistent differences. Sleep duration modified the effect: the PAS difference was most pronounced in short sleepers (+20.4%) and reversed in long sleepers (-10.8%, interaction p=0.06). SIGNIFICANCE: The surprising finding is that traditional HRV showed almost no difference between night-shift and day-shift workers. But a newer metric called heart rate fragmentation - specifically PAS, the percentage of intervals in alternation segments - was significantly elevated in night/rotating shift workers. Sleep duration modulated the severity of that fragmentation, suggesting that this metric captures autonomic stress that standard HRV indices miss. Read the full study 3. Weighted vest use increases cardiovascular workload and transiently suppresses HRV during active wearing, with more pronounced effects in females: ATLAS RCT sub-study PUBLICATION: Physiological Reports AUTHORS: Bellman, PA Jansson, JO Jansson, Ohlsson, and Bergfe...

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history. This week on This Week in Heart Rate Variability, we open a new themed month by looking at where heart rate variability is headed next. Six studies map the future of the field — from a unifying theory of cardiovascular instability built on Shannon entropy, to the regulatory and technical realities of validating consumer wearables, to a meta-analysis quantifying how far photoplethysmography still is from true electrocardiography-derived HRV, to a virtual reality study, a forest-based multimodal field study, and a deep dive into the asymmetric structure of the heartbeat itself. RESEARCH HIGHLIGHTS THIS WEEK 1. Shannon Entropy in Heart Rate Variability: A Unified Indicator of Electrical and Hemodynamic Cardiovascular Instability PUBLICATION: Medical Research Archives AUTHORS: Orazio Antonio Barra KEY FINDING: This systematic review pooled 22 published studies that applied Shannon entropy of RR intervals to atrial fibrillation and tilt-induced syncope. Entropy declined progressively across both conditions — roughly ten percent at baseline instability, fifteen to twenty percent approaching pre-crisis, and twenty-five to thirty percent as crisis became imminent — with entropy showing better specificity than other HRV indices while holding onto its sensitivity. SIGNIFICANCE: Entropy looks less like a metric tied to one specific condition and more like a general-purpose marker of autonomic complexity loss that shows up consistently whether the underlying instability is electrical or hemodynamic. This is a synthesis of existing studies rather than a new trial, so it should be read as a strong, well-supported hypothesis rather than a validated bedside tool. Read the full study: https://esmed.org/MRA/mra/article/view/7606 2. Validity, Reliability, and Regulatory Considerations for Consumer Devices in Clinical Research Data Collection PUBLICATION: Applied Clinical Trials Online AUTHORS: Lauren Crooks, Greta Marie van Schoor, Anthony Everhart, Bill Byrom, and Thijs Sondag KEY FINDING: This article maps the validity, reliability, and regulatory landscape for consumer wearables used in decentralized clinical trials. Heart rate accuracy can approach ECG-level concordance under favorable conditions, but motion artifacts, device-to-device variation, and demographic performance gaps can cause aggregate agreement statistics to mask large individual-level errors. Only an estimated 11% of devices on the market have been rigorously and publicly validated. SIGNIFICANCE: Regulators are converging on "fit-for-purpose" validation rather than universal accuracy claims — asking whether a specific device is accurate enough for a specific clinical question, not whether it's accurate for everything. That's a useful discipline for anyone using consumer devices outside a formal trial, too. Read the full study: https://www.appliedclinicaltrialsonline.com/view/validity-reliability-regulatory-considerations-consumer-devices-clinical-research-data-collection 3. Accuracy of Photoplethysmography-Derived Pulse Rate Variability Compared with Electrocardiography-Derived Heart Rate Variability: A Systematic R...

In this follow-up episode of the Heart Rate Variability Podcast, Matt Bennett reconnects with Lieven Van Linden to discuss the newly published English version of his book, Fully Charged. Since their last conversation two years ago, Lieven’s work has continued to evolve at the intersection of leadership, nervous system regulation, sustainable performance, and HRV. Lieven shares how his engineering background shaped the framework behind Fully Charged, applying process improvement thinking to human performance. Rather than treating energy, resilience, and leadership as vague concepts, his model looks at the body as a system with inputs, processes, outputs, and measurable feedback. HRV plays a central role as a biomarker for nervous system health, recovery, and available energy. Matt and Lieven also explore what has changed since the book's original publication, including new English-language chapters on artificial intelligence and women's energy levels. Lieven reflects on the slower-than-expected adoption of HRV technology in Europe and the growing conversation around AI health coaches. While AI can support education and insight, Lieven emphasizes that human connection remains essential for lasting behavioral change. The conversation also moves into Lieven’s personal evolution. After years of extreme endurance racing, he has shifted toward freediving, which challenges him in a very different way. Rather than pushing through suffering, freediving requires relaxation, self-regulation, inner awareness, and trust in the body.