In this episode, Matt Bennett talks with Dr. Richard Harris about his article: Single-case report: dynamic changes in cardiac function during shamanic journeying and Qigong meditation

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

In this episode, we dive deep into the latest research from late 2025 and explore the exploding field of Psychophysiology. We look at how Heart Rate Variability (HRV) is becoming the "master key" for detecting everything from complex emotions to psychosis. We also break down a massive new study on how antidepressants shift your physical metabolism, the effectiveness of "light-guided" breathing for office stress, and how VR gaming affects your autonomic nervous system.

Links & Resources Mentioned:

Clinical Psychiatry & Pharmacology

Breathing & Interventions

The Science of Stress & Emotion (HRV)

Physiology in Action (VR & Exercise)

This Week’s Studies:

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

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

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

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

Video link: https://youtu.be/3vn_TF-ezTE

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.

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

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.

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.

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).

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

Find the article here: https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2839605

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.

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.

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.

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/

Show Notes

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

Show Notes

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