Yep... on a weekday when I wake up at 5am I look at the clock and try to go back to sleep because I know that I HAVE to get up at 6:30 and I'm going to be working all day.
On the weekends I know that I can take an afternoon nap if I want to. :D If I happen to sleep in until 7 or 8 I feel like I've wasted half the day.