Maintaining recommended sleep throughout the week is associated with increased physical activity in children

Given evidence of weekday-weekend variability in children's sleep and associations with obesity there is rationale for exploring sleep in relation to weekday and weekend physical activity (PA) and examining whether weekday-weekend variations in sleep impact physical activity.Children's (n=856) physical activity was measured using accelerometry (Toronto; 2010-2011). Sleep was assessed via parental report and collapsed into three categories (<9h; 9-10h; ≥ 10 h) and differences in anthropometric and physical activity characteristics were assessed. Data were compared to determine whether sleep increased, decreased or was maintained across the week and relationships with activity and overweight/obesity were explored (cross-sectional analysis) after controlling for confounders.On weekdays, children who slept the least (<9h) were less active in terms of overall intensity than those attaining ≥ 10 h, and more were overweight/obese (p<0.05). On weekends, differences in light physical activity occurred at lower sleep levels. Weekday-weekend sleep regularity mattered; overall intensity was higher among those maintaining recommended sleep (>9h) compared to those engaging in weekend-catch-up-sleep.While sleep is associated with obesity and activity in children, relationships vary by day. Recommended weekday-weekend sleep (regularity) supports healthy activity and should be an important health-promoting strategy. Future studies using longitudinal designs (to establish causality) are recommended.