Jacques Montplaisir, of the University of Montreal and director of the Sleep Disorders Center at Sacre-Coeur Hospital, says the number of children who are overweight drops to 15 percent in children who sleep 10 hours a night and falls to 10 percent among those that sleep 11 hours.

Montplaisir suggests the lack of nightly sleep may affect the secretion of hormones and points out naps don't seem to compensate for the lack of sleep at night.

"When we sleep less, our stomach secretes more of the hormone that stimulates appetite," Montplaisir says in a statement. "And we also produce less of the hormone whose function is to reduce the intake of food."

In the same study, the researchers also find that inadequate sleep could lead to hyperactivity.

Twenty-two percent of children who slept fewer than 10 hours a night at age 2 1/2 suffered hyperactivity at age 6, which is twice the rate seen in those who slept 10 hours to 11 hours per night, the study said.

"In adults, inadequate sleep translates into sleepiness, but in children it creates excitement," Montplaisir explains.