Letting children sleep late on weekends and holidays might help them avoid becoming overweight or obese, a new study suggests.
Researchers in Hong Kong found that children who got less sleep tended to be heavier (as measured by body mass index or BMI) than children who slept more. But among children who slept less than eight hours a night, those who compensated for their weekday sleep deficit by sleeping late on weekends or holidays were significantly less likely to be overweight or obese.
The study, which confirmed previous research linking sleep deficits to obesity in children, also found that, on average, children slept significantly longer on weekends and holidays than on school weekdays. However, the overweight children tended to get less weekend/holiday sleep than their normal-weight peers.
“There’s a lot of evidence linking short sleep duration to higher body mass,” said Kristen Knutson, assistant professor of medicine at the University of Chicago, who was not involved in the study. The precise nature of the link between short sleep duration and obesity remains unclear, said Mary A. Carskadon, professor of psychiatry and human behaviour at Brown University’s Alpert Medical School in Providence, and director of chronobiology at Bradley Hospital in East Providence.
“Evidence has shown that there are changes in satiety and in levels of the hunger hormones leptin and ghrelin,” Carskadon said. “But there’s also evidence that kids who are not getting enough sleep get less physical activity, perhaps simply because they’re too tired. It’s just not cut-and-dried.”
The findings, published in the November issue of Pediatrics, could be helpful in preventing and managing childhood obesity, the authors noted.