摘要Objective:Examine effect of sleep duration on children's risk of overweight and obesity;and study associations between activities in the last hour before bedtime and sleep outcomes(sleep duration,sleep quality,and sleep onset latency).Methods:Children's data were recruited using a questionnaire survey from a nationally representative sample of children(n=10 279)in China in 2013-2016.Mixed-effects models were used to test associations among variables stratified by sex.Results:Sleep duration was positively associated with BMI in boys(p=0.04,P=0.021).Girls with short sleep durations(＜8 h/d)tended to have higher BMI values than those with normal sleep durations(8-9 h/d)(β=0.12,P=0.063).The top three activities were playing electronic devices(Factor 1),doing homework,and reading(combined as Factor 2).Factors 1 and 2 were both significantly associated with sleep duration(β=0.17,P＜0.001;β=-0.26,P＜0.001,respectively).Conclusion:Sleep duration seems to affect BMI in Chinese children.Using electronic devices and reading before bedtime influenced sleep duration.Good bedtime habits and sleep duration can help weight management in children.