The clock strikes nine on a Saturday morning and your children are still sawing logs. It may be tempting to jerk back the covers and get them moving. But those extra hours of shut-eye may actually be the key to fighting obesity.

Researchers in Hong Kong have found that children who sleep less are significantly heavier than their well-rested counterparts. This wasn’t a surprise… several studies have shown a link between a lack of sleep and weight.

But what set this study apart was that it showed that kids who slept less than eight hours a night during the week but compensated by sleeping in on weekends or holidays were significantly less likely to be overweight or obese.

Scientists distributed questionnaires to track the lifestyle, sleep habits and weight of nearly fifty-two-hundred children in Hong Kong, ages five to fifteen.

The researchers didn’t determine why the overweight and obese children were less likely to sleep in on holidays. Scientists say it could be biological, because a lack of sleep has been shown to affect the hormones that control hunger. Or it could be the sleep-deprived kids are simply too tired to be physically active.

Most child experts recommend children get between nine and a half and ten hours of sleep per night. Between sixteen and thirty-three percent of all children in the United States are considered obese, according to the American Academy of Child and Adolescent Psychology.

So turn off your child’s alarm clock on the weekend. Those extra hours of sleep may be more valuable than you ever suspected.