Most Saturday mornings, parents are banging on walls when the clock strikes noon and the children have yet to rise. The parents don’t want their children to grow to be lazy or sleep the day away.

But there may be a very good reason to let them sleep in. It could help fight fat.

According to the HealthDay Reporter, researchers in Hong Kong found that children who got less sleep had a tendency to be heavier than children who slept more – at least, when calculated by body mass index or BMI.

But the children who slept less than the recommended eight hours of sleep a night, and who made up for it on the weekends and holidays, were significantly less likely to be overweight or obese.

Rhonnie Kerns, director of child nutrition for Tahlequah Public Schools, said she couldn’t comment on the study, considering she had never heard of it.

But Heather Winn of the Oklahoma Cooperative Extension Service said moderation is key.

“I let mine [children] sleep in if they have had a very busy week or if they were up a little late,” she said. “But your calories in have to equal the calories out, or you will gain weight.

Winn said adequate sleep is important for children, as well as adults. But she thinks it’s the lifestyle pace to which Americans are accustomed is the culprit for weight gain and obesity.

“I know in our fast-paced society, we don’t eat right,” she said. “Typically when we eat fast food and aren’t exercising as much as we could to lose the calories, we are going to gain weight.”

Winn said she isn’t sure getting more sleep is the answer to fighting fat, though.

“I think moderation is key,” she said.

The researchers in the study didn’t determine why obese and overweight children were not as likely to sleep late on holidays or weekends, but they did notices the children spend more time doing home work and watching TV than the normal weight children.

And this brings the point back to Winn’s suggestion, that there just isn’t enough physical activity.

According to the story on Yahoo.com, the researchers urged extreme caution in the interpretation of their findings citing “an irregular sleep-wake schedule and insufficient sleep among school-aged children and adolescents has been documented with a variety of serious repercussions, including increased daytime sleepiness, academic difficulties, and mood and behavioral problems.”

But the exact link between lack of sleep and obesity is unclear, said Mary A. Carskadon, professor of psychiatry and human behavior at Brown University’s Alpert Medical School in Providence, R.I.

“Evidence has shown 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.”

And theory is a popular one. WebMD has a story on its website, also citing sleep studies done on more than 8,000 people.

The findings in that report are based on information gathered from the National Health and Nutrition Examination Survey I (NAHNES I).

James Gangwisch, Ph.D., with the Columbia University, said more work is needed to determine the sleep and obesity relationship, but researchers have some ideas.

According to a news release by Gangswisch, humans may have evolved to store fat in summer, which has short nights and a lot of food to prepare for the winter’s long nights, and historically, a more scarce food supply.

“As a result, sleeping less could serve as a trigger to the body to increase food intake and store fat,” he said.