title: Report on childhood obesity in China (10): association of sleep duration with obesity.
abstract: OBJECTIVE
  To explore the association of sleep duration with obesity among children in urban areas of China.
  
  
  METHODS
  A total of 6 576 children (3 293 boys and 3 283 girls) aged 7-11 years were randomly selected from 36 primary schools in 6 metropolitan cities in China. A 7-day Physical Activity Recall was used to assess the sleep duration and physical activity level. The height, weight, waist circumference (WC) and percentage of body fat (%BF, as determined by bioelectrical impedance analysis technique) were measured by following the standardized operation procedures. The information on demography, lifestyle and eating habits was collected with a self-administered questionnaire from participants and their parents.
  
  
  RESULTS
  The average sleep duration per night in the children was 9.7 h with the decreasing trends along with the increase of age (P < 0.05). The sleep duration was negatively associated with body mass index (BMI) and WC in both boys and girls after adjustment for confounders (beta value -0.23 and -0.82 for boys, -0.24 and -0.91 for girls, respectively, P < 0.01). However, no significant association of sleep duration with %BF was found. Children who slept less than 9.0 h per night had a higher risk for overweight and obesity (OR = 1.29, 95% CI: 1.01, 1.64) and abdominal obesity (OR=1.38, 95% CI: 1.04, 1.83) as compared with those who slept for 10.0-10.9 h.
  
  
  CONCLUSIONS
  Short sleep duration is associated with obesity. It is important to ensure adequate sleep duration of children and foster their healthy lifestyle at an early stage of life.
authors.affiliation: National Institute for Nutrition and Food Safety, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
authors.forename: Li Ping
authors.initials: LP
authors.lastname: Meng
authors.forename: Ai Ling
authors.initials: AL
authors.lastname: Liu
authors.forename: XiaoQi
authors.initials: X
authors.lastname: Hu
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Song Ming
authors.initials: SM
authors.lastname: Du
authors.forename: Hong Yun
authors.initials: HY
authors.lastname: Fang
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.forename: Gui Fa
authors.initials: GF
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Hong Wei
authors.initials: HW
authors.lastname: Guo
authors.forename: Lin
authors.initials: L
authors.lastname: Du
authors.forename: Guan Sheng
authors.initials: GS
authors.lastname: Ma
mesh_terms: D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D012890:Sleep; D011795:Surveys and Questionnaires