When young children miss out on sleep, they don't just get cranky. They also eat more, just like their parents do.

Without enough sleep, you eat more. One study even found that sleep-deprived individuals ate 500 calories a day more than usual, which is like eating an extra meal. But there have been few, if any, studies on children. Now a small study of preschoolers reveals that loss of sleep for them also leads to eating more.

On the day they lost sleep, children ate about 21% more calories than they normally did. The next day, they ate 14% more calories.

In the study, children ate more on the day they missed sleep and also on the next day — the recovery day.

The ten preschoolers all skipped their typical afternoon nap, and they went to bed a little over two hours later than usual that night. The next day, they were allowed to sleep as much as they wanted.

The children wore activity sensors on their wrist that recorded time in bed, total sleep and sleep quality. Parents logged what the children ate and drank, and how much. They received no instructions from the researchers about feeding their children other than to record what they ate.

On the day they lost sleep, children ate about 21% more calories than they normally did. The next day, they ate 14% more calories than typically. On the day they missed sleep, the calories were mainly from consuming more carbohydrates (26% increase); while the next day they consumed an extra 23% of fat. But the main finding was that they ate more on both days.

Just how much might poor sleep habits and lost sleep contribute to the increasing number of overweight children we've been seeing? Right now, no one knows. According to the researchers, this is the first study to measure the effect of sleep loss on what preschoolers eat. But eating more and gaining weight do usually go hand in hand.

About 30% of preschoolers do not get enough sleep, according to the National Sleep Foundation. And one recent estimate suggests 23% of U.S. children are either overweight or obese. It will take more studies to see how closely these two facts are linked. But it's something to think about the next time your child skips their nap. Or when your teen starts staying up later and later.

The study appears in the Journal of Sleep Research.