Children need sufficient sleep each night to function. But getting enough sleep might also affect other aspects of health, such as their weight.
A small recent study found that altering children's sleep experimentally resulted in changes in how much they ate.
The change in amount of sleep also slightly influenced the children's weight.
The children weighed slightly more (half a pound) at the end of the week when they got less sleep than at the end of the week with more sleep.
This study provides some evidence that not getting enough sleep could influence how much kids eat and weigh.
This study, led by Chantelle N. Hart, PhD, of the Psychiatry and Human Behavior department at Alpert Medical School of Brown University, aimed to learn how children's sleep affected aspects of their food intake and weight.
The researchers conducted a small study with 37 children, aged 8 to 11, over a three-week period.
Despite being small, the experiment was carefully designed, and each child was compared against himself or herself under different conditions.
Just over a quarter of the children (27 percent) were overweight or obese.
For the first week, the children all slept at home for the typical amount of sleep they usually got.
Then, they were randomly assigned to either get 1.5 more hours of sleep each night for a week or to get 1.5 fewer hours of sleep each night for a week.
During the third week, the children switched: if they had been getting 1.5 hours more, they then got 1.5 hours less.
The researchers then assessed several characteristics and outcomes among the children.
They determined what the children had eaten over a 24-hour period during each of the three weeks, and they assessed the levels of leptin and ghrelin in the children.
Leptin and ghrelin are two hormones that have to do with a person's appetite regulation. Leptin tells the body that it is full and does not need to eat. Ghrelin tells the body it is still hungry and needs to eat.
The researchers also assessed the children's weight and how hard they were willing to work to "earn" one of their favorite foods by playing a computer game for points toward the food.
The researchers found that the children ate less food (about 134 fewer calories a day) during weeks when they slept longer than during weeks with less sleep time.
Most of the additional food the children ate during the week when they were awake for more time was eaten during the period when they would have been asleep on the week with the greater amount of sleep.
On empty stomachs, the children's levels of leptin were lower when they had slept for longer than when they had slept a shorter amount of time.
There was no difference seen in ghrelin levels across the different weeks. The children also did not respond more or less to "reinforcement" — wanting their favorite food more — during any of the weeks.
However, the children weighed less, on average, at the end of the week with more sleep than at the end of the week with less sleep. The difference was an average 0.22 kilograms, or 0.5 pounds.
Therefore, this experiment's results appear to match up with other studies' findings that less sleep can affect how much a child eats and weighs.
"Increases in sleep duration in school-age children are associated with decreased reported energy intake, lower fasting leptin levels and weighing less," the authors wrote.
They suggested that more research be done to learn how changing a child's amount of nightly sleep might affect their weight over a longer period of time.
This study was published November 4 in the journal Pediatrics. The research was funded by the American Diabetes Association.
One author has received royalties from Lippincott for editing a book on children's sleep medicine and has consulted for Shire, Transcept, Jazz and Pfizer.
Another author has received research funds from Eli Lilly. The other authors had no potential conflicts of interest.