Association between physical activity and sleep indicators among adolescents

Purpose: The aim of the present study is to analyze the association between physical activity and sleep indicators among adolescents. Methods: Cross-sectional study involving 647 adolescents (53.0% female). Leisure time physical activity at low and at moderate to vigorous intensities (420 min/week) were the independent variables and the outcomes were daytime sleepiness, classroom sleepiness, poor sleep perception, sleep duration, bedtime, and wake up time. The multivariate association was performed by Poisson regression to estimate Prevalence Ratios (PR). Results: Not achieving 420 min/week of physical activity at light and at moderate to vigorous intensities was associated with a higher prevalence ratio for classroom sleepiness (PR=1.79 and 1.64), daytime sleepiness (PR=1.25 and 1.17), and poor sleep perception (PR=1.52 and 1.27), all P<0.05. However, not achieving 420 min/week showed the opposite association and decreased the prevalence ratio for having a sleep duration <8h (PR=0.74 and 0.72), P<0.05. No association was found between physical activity and bedtime or wake up time. Mediation analysis revealed that the association between physical activity and daytime sleepiness was fully mediated by a poor perception of sleep quality, while classroom sleepiness showed a partial mediation. Conclusion: Physical activity seems to have a positive effect on daytime sleepiness, classroom sleepiness, and perceived sleep quality. Poor sleep perception was the pathway through which physical activity was associated to sleepiness in the present sample. Conversely, physical activity reduced the likelihood of students achieving 8h of sleep.