Does the disclaimer "your results may vary" sound familiar? It should, because it follows nearly every weight-loss commercial (usually in a voice moving at the speed of light). As it turns out, sleeping should come with the same caveat. The amount of calories burned depends greatly on the person. This weight-loss calculator from FitWatch.com asked us to enter our weight and how long we planned to sleep. According to the ensuing calculations, a 160-pound person who sleeps eight hours will lose roughly 549 calories in the process. Not as much as I'd hoped, but not bad for doing nothing.
We usually burn about 600 calories in our sleep through breaking down food, repairing the body, and generally keeping our systems at the right temperature. Not bad for doing nothing... As far as calories go, a pound is usually about 3500 calories, so you're losing a few ounces every night. you definitely weigh less when you wake up in the morning because of a loss in water weight and your weight naturally fluctuates.