Aug. 4 (Bloomberg) -- Children who regularly skip an hour's sleep double their chances of being overweight, a study found.

Youngsters who miss an hour of the rapid eye-movement stage of sleep associated with dreaming face worse odds, tripling their risk for being overweight, according to the study of 335 children published today in the Archives of General Psychiatry.

Previous studies have shown that adults who sleep less than five hours a night tend to be overweight. Children and adults who don't get enough sleep have more time to snack, less energy for exercise and a craving for rich food, wrote the authors from the University of Pittsburgh School of Medicine. Tired people also produce a hormone linked to hunger, according to the study.

``We didn't know which stage of sleep was associated with obesity,'' said the study's lead author, Xianchen Liu, in a telephone interview today. ``And now we can confirm previous epidemiological studies showing a link'' between lack of sleep and obesity.

About 32 percent of children ages 2 to 18 were at risk for being overweight or obese from 2003 to 2006, according to data in the May 28 issue of the Journal of the American Medical Association. The number of overweight children tripled from 1980 to 2002, exposing youngsters to greater risks for diabetes and other weight-related health problems.

Parents should know how long children need to sleep and make sure television and the Internet don't disrupt bedtime, Liu said. Young children may need to sleep 13 hours or more, according to National Sleep Foundation guidelines, and adolescents need 10.

Regular times for bedtime and waking, even on weekends, will also allow children to fall asleep more quickly and enjoy a better quality of sleep, Liu said.

To contact the reporter on this story: Elizabeth Lopatto in New York at

elopatto@bloomberg.net.

Last Updated: August 4, 2008 16:00 EDT