There are generally only three reasons I'm ever awake at three am (as I am right now):
1) #1 – if you know what I mean.
2) If I can't sleep because we're going on vacation & I'm too excited.
3) I'm sick.
Judging from the Kleenex pile I have here, I'm going to go with #3, with just the slightest splash of #1 thrown in for good measure.