I haven't slept late since my son was born 7 years ago. At first, it was because he was waking me up. Now, it's because my body is trained to wake up early every damn day. Going out of town this weekend with no kid, I'll still wake up, workout/run, shower, and eat breakfast before my wife even thinks about waking up. Edit: I'm up to midnight-1:00 every night, too, so waking up early isn't because I go to bed early.