Researchers from Temple University found that when kids slept more than their usual amount for a week, they consumed fewer calories, had lower fasting levels of the hunger- and weight-regulating hormone leptin, and even weighed less.
"Given all of its documented benefits, in many ways, you can't lose in promoting a good night's sleep," study researcher Chantelle Hart, an associate professor of public health at the university's Center for Obesity Research and Education, said in a statement.
The three-week study, published in the journal Pediatrics, involved 37 kids between ages 8 and 11, about a quarter of whom were obese or overweight. For the first week, all the kids were asked to sleep their normal amount each night. For the second week, kids were assigned to either sleep 1.5 hours more than their normal amount, or 1.5 hours fewer than their normal amount. In the third week, the kids who were assigned to sleep less in the second week were asked to sleep more, while kids assigned to sleep more in the second week were asked to sleep less. Their sleep time was measured using wrist actigraphs.
Researchers found there was a difference of two hours and 21 minutes of sleep time between the "sleep less" condition and the "sleep more" condition. During the week the kids slept more, they consumed 134 fewer calories a day, on average, and also weighed half a pound less than the week when they slept less. They also had lower fasting levels of leptin during the week they slept more.
"Most of the difference in kcal intake occurred during the additional three hours that children were awake during the decrease condition with children reporting 103 kcal/day more during this time," the researchers noted in the study.
According to the National Sleep Foundation, school-aged children (ages 5 to 12) should get between 10 and 11 hours of sleep a night. Younger children need even more shuteye; preschoolers, for instance, should get 11 to 13 hours a night, and toddlers need 12 to 14 hours of sleep per 24-hour period.