Compositional analysis of 24-hour activity behaviors and perceived stress among older adults: Evidence from the China health and nutrition survey.

OBJECTIVES: This study examined how daily movement behaviors-sleep, sedentary behavior (SB), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA)-are associated with perceived stress in older adults. METHODS: Data were derived from the 2015 China Health and Nutrition Survey (CHNS). This study adopted a cross-sectional design. A total of 3892 older adults aged 60 years and above were included. Perceived stress was measured using the Perceived Stress Scale (PSS). 24-hour movement behaviors were assessed and classified by intensity based on metabolic equivalent of task (MET) values. Compositional regression and isotemporal substitution analyses were performed. RESULTS: Compositional regression showed the 24‑hour movement behavior composition was significantly associated with perceived stress, with higher proportions of MVPA, LPA, and SB linked to lower stress levels and a greater proportion of sleep linked to higher stress. The isotemporal substitution model that reallocating 30 min of sleep or SB to LPA was associated with the largest decrease in perceived stress (Δ = -0.319 and -0.384, respectively; p < 0.001). Replacing sleep or SB with MVPA also showed significant but smaller associations. Dose-response analysis revealed linear benefits across the 5-30 min range: stress reduction began with as little as 5 min of substitution and strengthened with longer durations. CONCLUSIONS: Replacing sedentary time or sleep with light physical activity-even briefly-was associated with lower perceived stress in older adults, with longer durations associated with greater decreases. These findings suggest time-based behavioral targets for future research rather than structured exercise prescriptions, pending confirmation in prospective studies.