Over the counter sleep aids?

last night, i couldnt sleep at all. i just kept tossing and turning for hours, and by the time i got to sleep it was 2 am, which is a problem because i need to be up at 5 am. this only happens to me once in a while though, and when it does, its terrible. i took some nyquil that night and a small dose of nyquil (10 ml) usually puts me to sleep pretty easily, but unfortunately it didnt work and i was laying in bed for an hour after i took it. i dont use nyquil a lot either, barely even once every few months. should i try an otc sleep aid? i was thinking either tylenol PM or a generic brand, but do different pills work for different people? what would you recommend?