I've heard that exercising right before bed isn't good for you. Better than staying up all night though, I suppose.

@ Mosh and Snowy: Do you guys use Melatonin to suppress REM in the first half of the night and then get the rebound in the second half, or do you take it one night and then get the rebound the second night? I seem to recall that Melatonin has a fairly short half-life.