I average 7 hours a night when in a "normal" state, 9 or 10 when I'm depressed, and 4 or 5 hours when I'm so manic that someone has to peel me off the ceiling. That is, of course, not a straight 4-5 hours, more like dozing and waking up multiple times. But I rarely go all night without at least SOME sleep, even though I can be pretty seriously manic sometimes.