Description

This Week in HRV - Episode 21

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...