Sleep and obesity in preschool children.

OBJECTIVE To examine the relationship between sleep and obesity in children 3 to 4 years old in Shanghai, China. STUDY DESIGN A total of 1311 Chinese children from 10 kindergarten classes in Shanghai, aged 3 to 4 years, who were participating in the kindergarten entrance health examination in 2000, were included in the study. Body weight and height were measured, and a questionnaire was given to the children's parents about sleep and physical and social characteristics of the children and their family. The main outcome measure was obesity, defined as body mass index (kg/m2) > or = 95th percentile for the children. RESULTS Compared with children reporting > or = 11 hours of sleep per night, the odds ratio for childhood obesity was 4.76 (95% CI, 1.28-17.69) for children with <9 hours of sleep, and 3.42 (95% CI, 1.12-10.46) for children with 9.0 to 9.4 hours of sleep, after adjustment for age, sex, and other risk factors. Children with caregivers who slept less, who had mothers with higher education, or who co-slept with caregivers had less nighttime sleep than other children. CONCLUSION Short sleep duration is positively associated with obesity in preschool children, and short nighttime sleep duration is significantly related to bedtime and co-sleeping with caregivers.