Washington, Feb 8 : A new study by researchers at the Johns Hopkins Bloomberg School of Public Health has revealed that less sleep can increase a child's risk of being overweight or obese.
The authors analysed epidemiological studies and found that with each additional hour of sleep, the risk of a child being overweight or obese dropped by 9 percent.
"Our analysis of the data shows a clear association between sleep duration and the risk for overweight or obesity in children. The risk declined with more sleep," said Youfa Wang, MD, PhD, senior author of the study and associate professor with the Bloomberg School's Center for Human Nutrition.
"Desirable sleep behavior may be an important low cost means for preventing childhood obesity and should be considered in future intervention studies.
"Our findings may also have important implications in societies where children do not have adequate sleep due to the pressure for academic excellence and where the prevalence of obesity is rising, such as in many East Asian countries," Wang added.
For the study, Wang and colleagues reviewed 17 published studies on sleep duration and childhood obesity and they analysed 11 of them in their meta-analysis. The recommended amount of daily sleep varied between studies analysed and with children's age.
Some research suggests that kids under age 5 should sleep for 11 hours or more per day, kids age 5 to 10 should sleep for 10 hours or more per day, and kids over age 10 should sleep at least 9 hours per day. The researchers used these recommendations for their analysis.
For kids under age 5, shortest sleep duration meant less than 9 hours of sleep per day. For children ages 5 to 10 it meant less than 8 hours of sleep per day and less than 7 hours of sleep per day for children over 10.
They found that kids with the shortest sleep duration had a 92 percent higher risk of being overweight or obese compared to children with longer sleep duration.
The researchers also found an association between increased sleep and reduced obesity risk was strongly associated with boys, but not in girls.
The study is published in the February 2008 edition Obesity, the journal of The Obesity Society.