I go to bed normally around four, I get up, usually, around eight - resp. - I wake up, I get up sometime after. : o I usually fall asleep without a problem and I get up anyway. And for trouble-free operation - this is enough for me in the long run. Sometimes, true (after some major ´nomaze´ - or within the post-monkey state), I need more sleep, I sleep 12-15 hours. On the other hand - I have no problem normally functioning for about three days without sleep, if necessary even longer (previously a week +).