Wait, let's think about this: exercise helps us lose weight, so does the opposite of exercise, sleep? It's almost true. More accurately, according to the Scientific American, a bad night's sleep encourages us to eat more, because it increases the production of the hunger hormone ghrelin and decreases the production of leptin, a hormone that tells us that we've eaten enough, thanks. Wait, there's more. Sciam also reports that sleep deprivation causes levels of the stress hormone cortisol to rise, which increases cravings for high-carb,
high-calorie “comfort foods.†And still more: the brain secretes growth
hormone during the deep-sleep phase, helping the body convert fat to
fuel. Without enough deep sleep, fat accumulates.