The obesity rate in the U.S. has more than tripled among 6 to 11-year-olds over the past three decades. A new study indicates that cutting down on REM sleep, a deep restorative form of rest, is associated with obesity among teens and children.

In the study, 335 children and teens were observed in a sleep clinic during three consecutive nights. The children who slept the least were the most likely to be overweight, and the less REM sleep they got, the greater the likelihood of obesity.

It could be that sleep loss changes the hormone levels in the body that may impact how much a person eats during the waking hours. Exhaustion may also influence levels of exercise.