Melatonin is interesting, I occasionally take it when I can't fall asleep, it generally works although I try not to use it too often. Occasionally, I wake up in the middle of the night tho and got into the habit of taking a 3mg melatonin pill to get me back to sleep. More often than not, the resulting sleep, probably around 4 hours left me feeling absolutely amazing, I mean better rested than I have been in years it was that big of a difference.

Of course sometimes it doesn't have that effect, but I've managed to repeat it 2-3 times and I know for a fact that simply being awake in the middle of the night and going back to sleep again doesn't have that effect.