[Jeebus]

Drinking is a big cause, once you sober up you wake up.

I have this problem alot of the time and normally I will wake up 4-6 hours after going to bed and 2-3 hours before I should get up. I lay in bed for a couple hours and fall asleep just to wake back up for whatever I got to do and then its real hard to get up. I found that if I just go ahead and get up at that time a few times in row it will take care of itself.