Melatonin is a hormone produced by the body. It has many uses, but here it applies to falling asleep and REM sleep. You can buy it at the drug store as a sleeping aid, but don't rely on it every night. If you use it too often your body will rely on the drug and not properly produce its own. It should definatly help you fall asleep though, its possible your lack of sleep may even be due to lack of melatonin in your body.