I'm with you--I sleep more than the cat does. I still get up at 8 to send DD off to school, but then often will go back to bed when she leaves at 8:35 and sleep until noon. Get up, eat, nap on the couch. Get up, fix dinner, fall asleep on couch while DH watches a movie and rubs my feet. Go to the real bed, do it all again.
I think that a lot of it has to do with not getting long, uninterrupted stretches of sleep. I know I'm getting up 4 or more times a night to pee and that lowers the quality of my sleep, so I need more quantity. Plus, I figure one of these nights I'm going to be in labor all night, so I should nap during the day just in case. How's that for rationalization?