Children who get too little sleep beginning at age three tend to be overweight five years later, warns a study linking sleep to obesity.
Doctoral student Emily Snell and colleagues at Northwestern University collected sleep data from a national sample of three to 12 year olds. Five years later they took a second look at 1,441 of those children, reported the online edition of health magazine WebMD.
"We found that even an hour of sleep makes a big difference in weight status," Snell said.
"Sleeping an additional hour reduced young children's chance of being overweight from 36 percent to 30 percent while it reduced older children's risk from 34 percent to 30 percent," she says.
The National Sleep Foundation recommends that five to 12 year olds get 10 to 11 hours of sleep each night. Teens should get eight to nine hours of sleep.
Snell and colleagues found that by their seventh birthday children were sleeping less than 10 hours on weekdays. This fell to eight-and-a-half hours by age 14, and to eight hours by 17.
Staying up too late was linked to later weight problems for three to eight years olds, and getting up too early for those in the 8-13 age group.
"Parents should be encouraged to put their younger children to bed early enough so they can sleep at least 10 or 11 hours a night," states the report published in journal Child Development.
"For older children, however, only later wake times were associated with lower rates of overweight. This result supports findings from the growing sleep literature encouraging later school start times, particularly for adolescents."