I tried Ambien, and I was not behaving well on that. It didn't make me sleep. 
Melatonin is something your body makes anyway, it just kind of ups the ante. Since I have issues calming my mind and falling asleep, I've noticed the melatonin quiets my brain enough so that i can fall asleep naturally. 
Unlike Ambien, which made me which as shit and still very much awake. 

I swear by melatonin. i love that stuff.