I don't have problems sleeping, but I've tried a few over the counter remedies (teas, etc) out of curiosity just to see if they would have an effect. For me, they didn't do anything. I felt completely unfazed, so I assumed they just don't work. But then I found this one tea called "Get Relaxed" by Republic of the Teas, and the flavor sounded interesting so I bought it. Never expected it to have any kind of effect, I was just after the taste, but every single time I drink it, I fall asleep less than 20 minutes later. And I'm not exaggerating, either. NOTHING works on me. Might be worth checking out.
And if you do happen to find something that helps, you might consider picking up a bottle of Valerian Root from the vitamin section of any drug store (I get it at WalMart for $4). It won't make you tired or anything, but once you do fall asleep, you will stay out all night and sleep really soundly. Just don't use it before work because it might make you sleep through your alarm :/