"Have you ever had a restless night followed by a day when no matter what you ate you never felt full or satisfied? If so, you probably experienced the working of leptin and ghrelin. Insufficient sleep drives leptin levels down, which means you don't feel as satisfied after you eat. Lack of sleep also causes ghrelin levels to rise, stimulating your appetite so you want more food."So its a double whammy. You don't feel satisfied and your appetite is revved up. So get lots of sleep! It also mentioned that with a lack of sleep your desire for high-carbohydrate, calorie-dense food increased. So, maybe that's what is helping with my weight loss this summer. I'm getting up at 8:00 instead of 6:00.