Timing of Moderate-to-Vigorous Physical Activity and Mortality Risk: Role of Chronotype and Sleep Patterns

AIMS: To examine whether diurnal timing patterns of moderate-to-vigorous physical activity (MVPA) are associated with mortality risk independent of activity volume, and whether these associations differ by chronotype and sleep midpoint. METHODS: and results This prospective cohort study included 75,509 UK Biobank participants (aged 40-73 years) with wrist-worn accelerometry and a median follow-up of 8.7 years. Participants not meeting the WHO MVPA guideline (<150 min/week) were classified as inactive; among guideline-adherent participants, K-means clustering of hourly MVPA distribution identified four active timing patterns (early-morning, consistently active, midday, and evening). Cox proportional hazards models were fitted for all-cause mortality (primary outcome) and cancer and CVD mortality (secondary outcomes). In the primary analysis restricted to guideline-adherent participants (reference = consistently active) and additionally adjusted for total MVPA volume, the midday-active pattern remained associated with a lower risk of all-cause mortality (HR 0.79, 95% CI 0.65-0.97; P=0.022), whereas associations with cancer and CVD mortality were attenuated and not statistically significant. Fine-Gray competing-risk models produced similar estimates for cause-specific mortality. In secondary analyses comparing active patterns with the inactive group, all active patterns were associated with substantially lower mortality risk, with the midday-active pattern showing the largest risk reductions. Stratified analyses by chronotype and sleep midpoint suggested that associations of timing patterns with mortality were less consistent in evening chronotype and later sleep midpoint strata. CONCLUSIONS: Among adults meeting MVPA guidelines, a midday-active pattern was associated with lower all-cause mortality independent of MVPA volume. Secondary comparisons confirm the broad benefit of meeting MVPA guidelines regardless of timing. These findings support considering both activity volume and timing when tailoring physical-activity guidance.