Less sleep can increase a childs risk of being
overweight or obese, according to a study by researchers
at the Johns Hopkins Bloomberg School of Public Health.
Their analysis of epidemiological studies found that with
each additional hour of sleep, the risk of a child being
overweight or obese dropped by 9 percent. The results
are published in the February 2008 edition Obesity, the
journal of The Obesity Society.
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 Schools 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
The influence of sleep quality on obesity risk
is another important area where future research is needed,
added Xiaoli Chen, MD, PhD, the studys lead author
and a former postdoctoral fellow at the Bloomberg School.
For the study, Wang, Chen and colleague May A. Beydoun,
also a postdoctoral fellow at the Bloomberg School, reviewed
17 published studies on sleep duration and childhood obesity
and they analyzed 11 of them in their meta-analysis.
The recommended amount of daily sleep varied between
studies analyzed and with childrens age. Some research
suggests that children under age 5 should sleep for 11
hours or more per day, children age 5 to 10 should sleep
for 10 hours or more per day, and children over age 10
should sleep at least 9 hours per day. The Hopkins researchers
used these suggestions for their analysis.
The results of the analysis showed that children with
the shortest sleep duration had a 92 percent higher risk
of being overweight or obese compared to children with
longer sleep duration. For children 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. The association between increased sleep
and reduced obesity risk was strongly associated with
boys, but not in girls.
Is Sleep Duration Associated with Childhood Obesity?
A Systematic Review and Meta-analysis was written
by Xiaoli Chen, May A. Beydoun and Youfa Wang. The study
was supported in part by the National Institute of Diabetes
and Digestive and Kidney Diseases, the U.S. Department
of Agriculture and the Johns Hopkins Bloomberg School
of Public Health.