I think it's quite the debateable subject. I have to disagree with you here, Blood&Iron. Go figure, right? I'd say 8 is somewhat of an arbitrary number that takes into account individual needs. Personally, when I start getting 9-10 hours a night I'm more tired than when I get about 7. I read a little snip it from Flavio Bacciani and he said that he only gets about 4 hours. Can't argue with his physique. I also remember something about Napoleon only getting around 3hours.