Red-eyed and weary

I've always had enormous difficulty falling asleep and staying that way for more than a couple of hours. This most craptacular condition has worsened now that I'm back in school. I simply can't turn my stupid brain off. The only sure way I've found to knock myself out for any duration is to take NyQuil. Obviously, this method has its flaws. First of all, I must take the NyQuil at least 12 hours before work or school to ensure the fog has dissipated enough to think properly. Secondly, NyQuil seems to heighten the strangeness of my dreams, which really don't need any help in that department. Thirdly, I'm pretty sure my liver resents me enough already.

Does anyone have a safe, legal solution to my trouble?