Relationships of Sleep Duration, Midpoint, and Variability with Physical Activity in the HCHS/SOL Sueño Ancillary Study.

OBJECTIVE/
BACKGROUND: Short and long sleep duration, later sleep midpoint, and greater intra-individual sleep variability are associated with lower physical activity, but previous research lacks objective and concurrent assessment of sleep and physical activity. This cross-sectional study examined whether sleep duration, midpoint, and variability in duration and midpoint were related to wrist actigraphy-measured physical activity. PARTICIPANTS: Participants were 2156 Hispanics/Latinos in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Sueño Ancillary Study.
METHODS: Participants wore Actiwatch devices to measure sleep and physical activity via the wrist for ≥5 days. Physical activity was defined as minutes/day in the upper quartile of the sampling distribution's non-sleep activity, capturing light to vigorous physical activity.
RESULTS: An inverse linear relationship between sleep duration and physical activity was found such that each additional sleep hour related to 29 fewer minutes of physical activity (B = -28.7, SE = 3.8), p < .01). Variability in sleep midpoint was also associated with physical activity; with each 1-hr increase in variability there were 24 more minutes of physical activity (B = 24.2, SE = 5.6, p < .01). In contrast, sleep midpoint and variability in duration were not associated with physical activity. Sensitivity analyses identified an association of short sleep duration and greater variability in sleep duration with greater accelerometry-derived moderate-to-vigorous physical activity measured at the HCHS/SOL baseline (M = 2.1 years before the sleep assessment).
CONCLUSIONS: Findings help clarify inconsistent prior research associating short sleep duration and sleep variability with greater health risks but also contribute novel information with simultaneous objective assessments.