Bidirectional Relations Between Physical Activity And Sleep In Adolescent Girls

PURPOSE: Adolescence is a developmental period accompanied by greater independence and autonomy regarding health behavior engagement. Adolescent girls experience higher rates of physical inactivity and disordered sleep compared to their male peers. Yet, few studies have used intensive longitudinal methods to explore relations between physical activity and sleep in this population. This study investigated bidirectional relations between physical activity and sleep in adolescent girls. METHODS: Adolescent girls (n = 66) age 12-18 years completed a 28-day daily diary study with assessments at the beginning and end of each day. Beginning of day assessments included the Consensus Sleep Diary-Core to assess sleep indices from the previous night. The end of day assessment included two single items modified from the International Physical Activity Questionnaire-Short Form to assess time spent in moderate and vigorous intensity physical activity (MVPA) that day. Sleep indices and MVPA were disaggregated to create between-person (i.e., grand-mean centered) and within-person (i.e., person-mean centered) variables. Multilevel models tested bidirectional relations between total sleep time and MVPA as well as sleep quality and MVPA controlling for age, body mass index, race, and day of week. RESULTS: At the within-person level, neither total sleep time nor sleep quality from the night before predicted MVPA that day (ps > 0.07). Similarly, MVPA on a given day was unrelated to total sleep time and sleep quality that evening (ps > 0.52). At the between-person level, sleep quality, but not total sleep time, was bidirectionally associated with MVPA. Girls who had better sleep quality overall, tended to engage in more MVPA on a given day (B = 26.56, SE = 13.31, p < 0.05) and girls who engaged in higher levels of MVPA overall, tended to report better sleep quality on a given day (B = 0.002, SE = 0.001, p < 0.05). CONCLUSIONS: Although there was no evidence of relations between physical activity and sleep at the within-person level, results indicated bidirectional relations between physical activity and sleep quality at the between-person level. Future research should explore relations between additional sleep indices and physical activity as well as relations when employing device-based measures of physical activity and sleep. Funding for this study was provided by the University of North Carolina Greensboro School of Health and Human Sciences' Research Excellence Award