"Most over-the-counter sleep aids have (diphenhydramine), a kind of antihistamine, in them" . . . Diphenhydramine is the ingredient in the brand-name drug Benadryl. "Benadryl makes you sleepy but it doesn't give you a deep, restful sleep." And because some diphenhydramine remains in a person's body even after he or she wakes up, many people feel like they have a mild "hangover" in the morning . . . . "the most common sleep aid is alcohol — people have a drink before bed thinking it'll put them to sleep. But alcohol's effect is gone in four or five hours and then you wake up. People take sleep aids for the same reason. They may knock you out, but it's unconsciousness, not sound sleep.
The benefits of melatonin as a sleep aid are disputed. Warm milk works at least as well as many over the counter sleep aids.