Seasonal variation in resting heart rate and heart rate variability is attenuated with advancing age

Q: What are the key findings of this study?

Advancing age attenuated seasonal amplitudes in resting heart rate by ~29% (1.55 vs 2.18 bpm) and heart rate variability by ~48% (3.05 vs 5.84 ms) in older versus younger adults.

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Cardiovascular autonomic physiology in free-living adults (n=16415). Intervention: Advancing age (older adults aged 60-79 years vs younger adults aged 18-39 years) across seasonal variations vs. Younger adults (18-39 years) and middle-aged adults (40-59 years). Primary outcome: Seasonal peak-to-trough amplitude of nocturnal resting heart rate (RHRamp) and heart rate variability (HRVamp, RMSSD) (95% CI 1.45-1.65, p=<0.001).

Q: What question did this study set out to answer?

To characterize seasonal variation in resting heart rate and heart rate variability and assess how behavioral covariates and individual traits moderate these patterns.

William E. Jennings; Nathaniel D.M. Jenkins; William von Hippel; Finnbarr Fielding; Christopher J Chapman; Dylan J. Curran; Lauren R. Parola; Jenna G. Cohen; Christian P. Cheung; Kristen Erika Holmes; Josh Leota; Ursula Konstantin Beattie; Summer R. Jasinski; Seth Elkin-Frankston; S. Tony Wolf; Gregory J. Grosicki

doi:10.1038/s41514-026-00552-w

October 31, 2026npj AgingOpen Access

Seasonal variation in resting heart rate and heart rate variability is attenuated with advancing age

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Key result

Older age is linked to ~29% lower seasonal variation in resting heart rate.

95% CI 1.45-1.65
P<0.001
n=16,415

Why the study?

The factors driving seasonal variation in cardiovascular physiology, including resting heart rate and heart rate variability, are poorly understood.

Does advancing age, biological sex, BMI, or physical activity moderate seasonal variation in resting heart rate and heart rate variability in U.S. adults?

Key Points

To characterize seasonal variation in resting heart rate and heart rate variability and assess how behavioral covariates and individual traits moderate these patterns.
Analyzed 1 year of continuous wearable device data from 16,415 U.S. adults (9,000 males, 7,415 females) spanning 5,884,872 person-days across young (18–39 years), middle-aged (40–59 years), and older (60–79 years) groups.
Used generalized additive mixed models (GAMMs) and linear mixed-effects models to evaluate seasonal amplitudes, adjusting for sex, body mass index (BMI), physical activity, and sleep metrics.
Population-level resting heart rate reached its nadir in August and peaked in December with an amplitude of 2.00 bpm (95% CI: 1.94, 2.05), while heart rate variability peaked in August and troughed in December with an amplitude of 4.17 ms (95% CI: 4.01, 4.34).
Seasonal amplitude declined across age groups for resting heart rate (young: 2.18 bpm; middle-aged: 2.05 bpm; older: 1.55 bpm; Ps <= 0.046) and heart rate variability (young: 5.84 ms; middle-aged: 4.08 ms; older: 3.05 ms; Ps < 0.002).
Physical activity and sleep each accounted for <10% of seasonal patterns; amplitudes were ~29% and ~48% lower in older versus younger adults, did not differ by biological sex after age adjustment, and were larger with higher physical activity and lower BMI.

Study Design

Type

Cohort (n=16,415)

Structured PICO

Does advancing age, biological sex, BMI, or physical activity moderate seasonal variation in resting heart rate and heart rate variability in U.S. adults?

P

Population

16,415 U.S. adults (mean age 46.0 years, 45.2% female) using continuous wearable monitoring (≥24 valid days/month) followed for 1 year (5,884,872 person-days).

E

Exposure

Seasonal environmental exposure and continuous monitoring via WHOOP wearable device over 1 calendar year

O

Outcome

Seasonal variation (peak-to-trough amplitude of the modeled annual trajectory) in nocturnal resting heart rate (RHR) and heart rate variability (HRV, measured as RMSSD) over 1 calendar yearsurrogate

Main Result

Absolute Event Rate: 1.55% vs 2.18%

p-value: p=<0.001

Continuous wearable monitoring in 16,415 adults demonstrates robust seasonal variations in resting heart rate and heart rate variability that are largely independent of sleep and physical activity fluctuations, but are significantly attenuated with advancing age, higher BMI, and lower habitual activity, suggesting that greater seasonal autonomic variation reflects preserved cardiovascular plasticity.

Limitations

WHOOP subscribers likely represent a more health-conscious and higher-socioeconomic-status subset of U.S. adults, limiting generalizability
RHR and HRV were derived from wrist-worn photoplethysmography rather than electrocardiography
BMI was derived from self-reported height and weight at a single time point
Environmental exposures (ambient temperature, humidity, air quality) were not measured at the individual level
Clinical endpoints, blood pressure, medication use, and diagnosed cardiovascular disease were unavailable
Cross-sectional comparisons across age groups rather than longitudinal within-individual aging trajectories
Older females were underrepresented (n=1,415 vs. n=3,000 in other age × sex strata) due to demographic asymmetries of the WHOOP wearable platform
Lack of menstrual-cycle and menopause-status data
Absence of individual-level residential data; photoperiod exposure was approximated using state-centroid latitude, limiting contrasts to between-state variation

Implication

Age attenuates seasonal RHR/HRV amplitudes and should not yet alter monitoring; leaves open links to cardiovascular plasticity.

Abstract

The factors driving seasonal variation in cardiovascular physiology are poorly understood. Using one year of continuous wearable data from 16,415 U.S. adults (5,884,872 person-days), we characterized seasonal variation in resting heart rate (RHR) and heart rate variability (HRV) and tested behavioral covariates (physical activity, sleep) and individual moderators (age, sex, BMI, habitual physical activity). RHR and HRV showed robust seasonal patterns (lower RHR, higher HRV in summer than winter), with seasonal amplitudes (peak-to-trough) of 2.0 bpm and 4.2 ms, respectively. Physical activity and sleep each accounted for <10% of these seasonal patterns, suggesting that other factors are primarily responsible. Seasonal amplitude, however, varied systematically across individuals. It was moderated by age (~29% and ~48% lower in older than younger adults) but not sex, and was greater in more active individuals with lower BMI, consistent with greater cardiovascular plasticity.

Discussion

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Cite This Study

Jennings et al. (2026) conducted a cohort in Cardiovascular autonomic physiology in free-living adults (n=16,415). Advancing age (older adults aged 60-79 years vs younger adults aged 18-39 years) across seasonal variations vs. Younger adults (18-39 years) and middle-aged adults (40-59 years) was evaluated on Seasonal peak-to-trough amplitude of nocturnal resting heart rate (RHRamp) and heart rate variability (HRVamp, RMSSD) (95% CI 1.45-1.65, p=<0.001). Advancing age attenuated seasonal amplitudes in resting heart rate by ~29% (1.55 vs 2.18 bpm) and heart rate variability by ~48% (3.05 vs 5.84 ms) in older versus younger adults.

synapsesocial.com/papers/6ae7d421edffb496294104b5 https://doi.org/10.1038/s41514-026-00552-w

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Seasonal variation in resting heart rate and heart rate variability is attenuated with advancing age

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Seasonal variation in resting heart rate and heart rate variability is attenuated with advancing age

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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