That doesn't mean sleep is the answer to the U.S. obesity epidemic, but it might be one part of the solution, according to study author Chantelle Hart, an associate professor of public health at Temple University's Center for Obesity Research and Education in Philadelphia.
The three-week study of 37 children, aged 8 to 11, suggests that increasing sleep could decrease food intake and improve weight regulation in this age group, she said.
Hart said the next step is looking at whether getting more sleep over a longer period might have even more dramatic effect on weight.
"Achieving a good night's sleep during childhood should be explored as an important strategy to enhance prevention and intervention approaches for obesity," she said.
Another expert supports that approach.
"The evidence is incredibly strong and consistent that a short list of lifestyle factors has a phenomenal influence on weight, health and even gene expression," said Dr. David Katz, director of the Yale University Prevention Research Center in New Haven, Conn.
The list includes physical activity, eating a healthy diet, not smoking, getting enough sleep and reducing stress, he said.
"The power of lifestyle as medicine is not adequately appreciated," Katz said. "As this study shows, the best way to improve diet and weight may be by improving sleep."
The link between sleep and weight was well-known already. "But I am aware of no other study showing as clearly that with a willful change in sleep pattern comes an impressive, concurrent change in appetite, hormonal balance and food intake," Katz said. "How well and how much our kids sleep may well influence how well and how much our kids eat."
In the United States, more than one third of children and teens are overweight or obese, which puts them at risk of serious health problems in adulthood.
For this study, published online Nov. 4 and in the December print issue of the journal Pediatrics, Hart's team started by letting the children sleep their usual amount, about 9.5 hours, for a week. Then they randomly assigned the kids to either boost their time in bed by 1.5 hours or decrease it by 1.5 hours. After a week, the groups swapped sleep routines.
Ten of the children (27 percent) were overweight or obese at the start of the study.
The children who added sleep ate less, an average 134 fewer calories a day, the study found. And they shed about half a pound on average and had lower morning levels of the hormone leptin. Leptin has been tied to appetite regulation.
While adults can get by with eight hours of sleep, children and teens need more, according to the National Sleep Foundation.
School-aged children should sleep 10 to 11 hours a night, while teens need about 9.25 hours of sleep nightly, the sleep foundation says.
Exactly why more shuteye might aid weight control isn't clear. It's possible that after a good night's sleep, children are more active during the day, said Hart, who was at the Miriam Hospital and Alpert Medical School of Brown University when she conducted the study.
She said the researchers are assessing activity changes within the context of this study but don't have final data yet.
Dr. Luis Gonzalez-Mendoza, director of pediatric endocrinology at Miami Children's Hospital in Florida, said trying to pick out all the factors that influence appetite is a very difficult task.
"Appetite is multi-factorial," he said. "I don't think this study was conclusive, but I think they opened the door to look at all these things."
To learn more about childhood obesity, visit the U.S. National Library of Medicine.
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