Researchers say the less you sleep, the more likely you are to produce too much of a hormone that stimulates appetite -- and too little of a hormone that makes you feel full.
Two studies report that sleep loss can contribute to obesity. Researchers found that when men slept 10 hours, they awoke with normal appetites. But when they slept only four hours they were hungry. And what they wanted to eat wasn't lean meats, fruits or vegetables. NPR's Patricia Neighmond reports.