I do the same thing after a show/performance/even rehearsals - pretty much every time I do anything artistic

. Anyways, I do yoga, or even just breathing exercises. Anything meditative that can calm your mind is key. People recommend not to take showers late at night, but for some reason that's the only way I can calm down and claim my highly prized 2-4 hours of sleep. Carbohydrates (Italian food!! - pastas, etc. (man I love my mother

)) will help you sleep as well, but don't eat after 6 or 7 (if you're stretching it).
There's a thread somewhere on here about insomnia, and Thal had some good advice, but I don't know where it is. . . .
So, essentially, RELAX and eat lots of carbs! (not a bad life, eh?)
~Ess~