The Siblings Who Refused to Go to Bed: Leptin and Ghrelin Leptin and Ghrelin are hormones. These cute little guys are from the neuroendocrine system. The neuroendocrine system is the system in our bodies responsible for controlling our appetites! That is worth repeating. The neuroendocrine system is responsible for managing our appetites. (Ever notice that when you are sleep deprived, you crave carbs? Read on...) Leptin tells our brain, "Ok, I am good to go. I am full. I don't need any more food right now." Leptin tells us when we are satisfied - commonly called the satiety factor. However, when we are sleep deprived, Leptin is decreased. In short, less sleep equals a decrease in food being able to satisfy us, which leads to overeating and weight gain. Ghrelin signals our caloric needs. Ghrelin tells us when to eat and how much to eat. Lack of sleep increases Ghrelin, thereby increasing the need to eat more. Decreases in Leptin and increases in Ghrelin, caused by sleep lo