Temporal Associations Between Sleep and Physical Activity Among Overweight/Obese Youth

Examine average interindividual and temporal intraindividual associations between time of sleep onset (sleep onset), total sleep time (TST), and minutes in moderate-to-very-vigorous physical activity per hour (MVPA/h) among overweight/obese youth. Overweight/obese youth (n = 134; 7-12 years) wore an accelerometer for 16+ hr/day, 5-7 days, which provided daily objective estimates of MVPA/h, TST, and sleep onset. Multilevel models revealed an intraindividual effect of TST, such that nights with longer TST preceded less MVPA/h during the midnight-to-midnight monitoring period; a significant random effect qualified this relationship. Average interindividual TST did not predict mean MVPA/h, whereas sleep onset significantly predicted mean MVPA/h. Later time of sleep onset (as opposed to TST) was the strongest predictor of group-level decreased physical activity. At the individual level, longer TST than usual predicted less MVPA/h than usual. Results suggest the need for more person-centered research and a greater focus on sleep timing among youth.