Average probably 5-6 hours, on balance. I admit I'm a bit amazed to see the number of folks who report sleeping 10 or more hours a night; I've been assuming no

Average probably 5-6 hours, on balance. I admit I'm a bit amazed to see the number of folks who report sleeping 10 or more hours a night; I've been assuming normal sleeping habits were around 8 hours a night. Personally, I do best on 8 a night (i.e., waking without an alarm), but I sacrifice quite a bit of sleep trying to work more or less full time but also be a more or less full-time parent to a 4-year-old and a 7-month-old. The trickiest part is finding long unbroken stretches of time to concentrate on harder problems; I can manage emails while distracted, or in short bursts, and simpler coding tasks, but solving trickier problems usually happens in the middle of the night. I tend to alternate sleeping 2-3 hours one night (e.g., 6-8am), then 7-8 the next. I feel mostly normal even on the days when I'm running a more serious deficit and don't generally feel sleepy during the day, though I can tell when the side-effects (reduced patience, mental errors, etc.) are creeping up more, and I'll try to spend a few nights in a row sleeping more. I don't generally drink anything caffeinated, particularly when I'm running on little sleep, or if I'm planning on staying up to work -- it seems to affect me much more when I'm seriously sleep-deprived, giving me an unpleasant jittery feeling; the worst part is that I can't sleep when I want to, but my concentration is ruined, so there's no longer any point to staying awake.