SAT-854 - The Declining Arc of Heart Rate Variability: What Children Teach US About Stress and Modern Life

Background: Heart rate variability (HRV) is a well-established marker of autonomic nervous system regulation and physiological resilience. In healthy children and adolescents, HRV is typically high, reflecting strong vagal modulation and neurocardiac flexibility. Across the lifespan, however, HRV declines. Whether this decline reflects normal biological maturation alone or is also shaped by cumulative exposure to psychosocial and environmental stressors remains insufficiently explored.

Methods: We conducted a cross-sectional observational analysis of 175.047 HRV recordings (116479 females, 58568 males) obtained using the PPG Stress Flow medical device (BioTekna, Marcon, Venice, Italy). HRV was quantified using the root mean square of successive differences (RMSSD), a robust index of parasympathetic activity. Data were stratified by age group and sex, and the population-level trajectory of RMSSD from late childhood through middle adulthood was examined using graphical and descriptive statistical methods.

Results: RMSSD values were highest in pediatric and adolescent age groups, consistent with a highly plastic and adaptable autonomic profile. From early adulthood onward, RMSSD declined progressively, with a steeper reduction observed during midlife. The lowest values were reached between the fifth and sixth decades of life. This pattern was consistent across sexes, although absolute values differed.

Discussion: While part of this decline likely reflects normative neurobiological maturation and age-related shifts in autonomic balance, the magnitude and slope of the observed reduction suggest additional influences. Contemporary childhood and adolescence are increasingly characterized by chronic low-grade stressors, including academic pressure, high screen exposure, reduced physical activity, sleep deprivation, and psychosocial strain. These factors may accelerate autonomic aging and contribute to what can be conceptualized as an increasing “allostatic” or “cacostatic” load, manifested as persistently reduced HRV in adulthood.

Conclusions: HRV appears to function not only as a marker of biological aging but also as a cumulative record of stress exposure and lifestyle patterns across the lifespan. The progressive decline in HRV may, therefore, reflect a physiological imprint of modern life. These findings underscore the need for early-life interventions aimed at preserving autonomic flexibility through stress reduction, physical activity, sleep hygiene, and supportive psychosocial environments. HRV may serve as a valuable integrative biomarker for monitoring population-level stress burden and guiding preventive strategies.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*