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Background: Information on the relationship between sleep duration and obesity among children in urban Guangzhou, China is limited. This study aims to examine the relationship between sleep duration and obesity in children aged 6-18 years.Methods: The sample consisted of 11,830 children aged 6-18 years. The children were randomly selected from 13 schools in three urban districts of Guangzhou. The study was conducted from September to November 2013. The height and weight of the children were measured. Adiposity status was estimated using body mass index and according to the cut point in China criteria. In the structured questionnaire, children reported daily sleep hours (less than 7 h, 7-9 h and more than 9 h), weekly food intake amount (including vegetables, fruit, sugar beverages and meat), physical activity and sedentary time. A caretaker would answer the questionnaire on behalf of a child aged below nine.Results: A total of 8,760 children (49.0 % boys) completed the study. The prevalence of obesity was 8.4 % (9.8 % in boys and 5.7 % in girls). Adjusted for age, diet and physical activity/sedentary behaviour, the odds ratio (OR) for obesity comparing sleeping <7 h (short sleep duration, SSD) with ≥9 h (long sleep duration, LSD) was 0.70 (95 % CI: 0.69-0.72) among boys and 1.73 (95 % CI: 1.71-1.74) among girls. Stratified by age, OR for boys aged 6-12 years comparing SSD with LSD was 0.60 (95 % CI: 0.55-0.66); by contrast, OR was 1.33 (95 % CI: 1.30-1.37) for boys aged 13-18 years.Conclusion: Short sleep duration is associated with increased chances of obesity among girls and 13- to 18-year-old boys, but the chances of obesity are decreased among 6- to 12-year-old boys. Age and gender should be regarded as specific characteristics for the effects of short sleep on obesity. [ABSTRACT FROM AUTHOR]

Background: The relationship between sleep duration and food intake is unclear. This study aims to examine the relationship among children aged 6-17 years in China.Methods: The sample consisted of 70,519 children aged 6-17 years, which were randomly selected from 7 representative areas from China, from September to November, 2013. In the structured questionnaire, children reported daily sleep hours (less than 7 h, 7-9 h and more than 9 h), weekly food intake amount (including vegetables, fruit, sugar beverages and meat), physical activity and sedentary time. The relationship of sleep duration with vegetable, sugar beverage, fruit and meat intake was evaluated by multi-nominal logistic regression and multi-variable adjusted.Results: A total of 62,517 children (51.6% boys) completed the study. Short sleep duration (SSD, < 7 h) was independently associated with increased sugar beverage intake (SBI, Odd Ratio, OR: 1.29, 95% CI: 1.19-1.40) but decreased vegetable (VI, OR: 0.94, 95% CI: 0.90-0.98) & fruit intake (FI, OR: 0.94, 95% CI: 0.88-0.99). Stratified by age and gender, SSD increased SBI for boys of both young (6-12 years) & older (13-17 years) groups and older girls (ORs: 1.25, 1.25, 1.49, 95% CI: 1.08-1.44, 1.04-1.50, 1.22-1.81, respectively), but decreased VI and FI for older girls (ORs: 0.84& 0.81, 95% CI: 0.74-0.96& 0.68-0.96, respectively).Conclusions: Among school-aged children in China, short sleep duration was associated with increased risks of more sugar beverage intake among those younger and boys but less vegetable & fruit intake among those older and girls. Longitudinal research is needed to clarify the causation in between. [ABSTRACT FROM AUTHOR]