Temporal relationships between device-derived sedentary behavior, physical activity, and sleep in early childhood.

STUDY
OBJECTIVES: Understanding the ideal composition of a child's day requires a better understanding of the relations between wake behaviors (sedentary behavior [SB], physical activity [PA]) and sleep. Here, we examine between- and within-person temporal associations between daytime wake behaviors and overnight sleep in early childhood, an important age when healthy behaviors are initiated and 24-hour behaviors are largely determined by caregivers.
METHODS: Daily, repeated measures of wake behavior and overnight sleep were assessed via wrist-worn actigraphy (mean = 9 days/nights) in 240 children (50.8 ± 9.8 months). Multilevel models with lagged effects were used to examine the temporal associations between wake and overnight sleep measures and adjusted for daily nap duration, age, sex, and socioeconomic status.
RESULTS: Between-person associations for sleep outcomes were negative between moderate-to vigorous-intensity PA (MVPA) and total activity for sleep efficiency (SE). Between-person associations for wake outcomes were positive between sleep duration and light PA, and negative between SE and both MVPA and total PA. When children obtained higher SE relative to their individual average, they were more likely to engage in less SB and greater MVPA and total PA the next day.
CONCLUSIONS: Generally, days with greater activity or sleep were not associated with greater subsequent sleep or PA. Most subsequent behaviors were not influenced by children achieving higher activity or sleep relative to their individual average levels, although higher SE was beneficially associated with next day wake behaviors. Future analyses with young children should consider within-person associations and could investigate lagged effects beyond one day.