And as a night owl, I can not fall asleep before 2-3ish am, but I have to be at work by 8 or 8:30, so I'm constantly working with some sleep deprivation.
Personally I am super productive from about 9pm to 2-3am.
But I need to be at the client at a reasonable hour (9am-9:30am).
Lately I've taken to hacking away from about 9pm to midnight then going to bed so that I can keep everyone happy. Of course, I tend to toss and turn a bit because there is always something that my mind is chewing on that I left off at midnight.
Weekends, all bets are off and my sleep schedule gets totally messed up with late nights and early mornings (2 year old kid). Ugh, I am not 18 any more :)
I find that reading a fiction book, even just a few pages, helps flush my brain's "cache" and relax.
Exercising a lot helps me fall asleep better at night. Lately i've been too busy with work to get much in, and i'm having a hell of a time falling asleep. When I train for something (some sort of race) I sleep like a baby.