. . . has been my personal motto -- perhaps mantra -- for many years. Graduate student days saw all-nighters an at least once, sometimes twice, per week occurence. While skipping sleep altogether like that is now past history, I've regularly gone for long spells on only 4 or 5 hours of sleep over a week.
Perhaps now I should new studies suggesting sleep is not taking seriously enough - and that even if should be prescribed (see here). Philosophy might never sleep - there is always more to say, to develop, to engage - but perhaps philosophers should.