I used to have the same problem, and it's always my mind racing...

I used to take a nightcap of Vodka, but it didn't really help a whole lot. Sleeping pills would make me drowsy, but I still couldn't fall asleep.

The problem has somewhat gone away, but I still get it on my days off... It's funny, I get more sleep when I'm working.

My sometime solution was to pull an all-night, and go to bed earlier that night (like Shinto said).