Article is at http://www.newyorker.com/archive/1999/08/02/1999_08_02_057_T...
You can search for the phrase "He goes to bed somewhere around eleven at night and rises at 4:30 A.M".
Say you sleep 2 hours less than "the norm". That means you get an extra 30 DAYS a year of 'awake' time. Over 50 years, that 2 hours has added up to an extra 4 years of useful awake time.
Would you rather have more time while you're young, and able to do stuff, or just live a bit longer when you're old and stuck in a home? (Assuming you're correct, and lack of sleep makes you die younger).
Everything in moderation - don't take things to extremes, but I'd say 5 hours is probably still healthy enough.
Having kids certainly helps with training yourself to not need much sleep.
Also, to me it makes intuitive sense that degeneration can be exponential. So a lil bit of carelessness all the time can accrue some major interest (ie. if you're outspending your body's budget on regeneration costs per day).
Oh damn now he's puked all over the laptop dammit. Eugh he has spots on his ear wonder if that's ok. Oh great now the nappy has exploded. Oh great now this bottle leaks.
But granted, some of it you can do semi conscious.
Additionally, I'm convinced that your dreams, whether you remember them or not, influence your consciousness. That great idea you had may be a derivative of some really strange thoughts that went through your head while you were asleep.
The point is that sleeping isn't wasted time. There's really important things going on and the ones sleeping those 30 more days a year are probably going to get more out of their sleep than those staying awake for that time.
With exercise, 6-7 hours. Without, 7-8 hours.