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.

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

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

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

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

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

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.

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