Many hormones are affected by sleep and follow a characteristic pattern over a 24 hour period.. For example, melatonin is the "hormone of darkness" that lets the brain know it is getting dark and it is time to prepare for sleep. As it is released in the evening hours, people become drowsy. Human growth hormone, which encourages cell repair in adults, is released during deep sleep. Indeed, hormone levels are affected by sleep, the time of day and by sleep deprivation. Two hormones have been implicated in the effects of sleep on weight. These are leptin and ghrelin.

Leptin and ghrelin work together to control appetite. Ghrelin is released by the gastrointestinal tract and stimulates appetite. Leptin is released by fat cells and signals the brain that you have taken in enough nutrition. You can see how an imbalance in these two would negatively affect hunger and the drive to eat. In fact, lack of sleep decreases leptin levels, while raising ghrelin levels. This will make you feel both hungrier and less satisfied after eating.

Insomnia, sleep deprivation and sleep apnea are all sleep problems that interfere with getting adequate sleep. In the case of sleep apnea, a perverse cycle may be set up in which poor sleep leads to weight gain that contributes to sleep apnea that fragments sleep which contributes to weight gain and so on. Interestingly, obese women may be protected somewhat from developing sleep apnea, because leptin may also stimulate breathing. With extreme obesity, however, the brain's breathing centers may stop responding to this effect of leptin. Thus leptin resistance in extremely obese women may contribute to the development of breathing problems.

So, to use the sleep diet what do you do? It seems that the simple answer is to make good sleep a priority. Try to get seven and a half to eight hours of sleep per night. Of course, exercise and good nutrition can't hurt either.