Melatonin

I've been taking it about an hour before bed for two weeks, and it does help me fall asleep faster, though the effect fades if I use it two nights in a row – I have to skip a day for it to work again.

It works well enough for nights when my mind won't shut off, but I don't feel it does much more than nudge me toward drowsiness. I've tried it on restless nights and it helps me fall asleep, yet I still wake up groggy a few hours later. Fine for occasional use, nothing magical.