I don't get enough sleep. Sucks. I can "be present" physically, but my mind just doesn't work. My body doesn't heal and I can't concentrate on music. And no emotions -- it's like being a zombie literally. Over time you can learn to live with this, but it can still be torture cutting back on sleep.
I know people who get very little sleep. (Darn them!) They get a lot done, but are on the tense side (probably a heart attack waiting to happen). I believe you can learn to function with less sleep and could be completely normal after some time. In the process however... you would have to be sure to put everything back. If you lost your emotions and lived like that for some time until it became a habit, I imagine you would keep that emotionless habit even when you got more sleep because it's something you learned. Scary thought. Those people that function with little sleep seem to be extremely active I've noticed. Occasionally I get stuck and have to get by with less sleep. It sucks. I would like to learn to function with less sleep just to get more stuff done, but I haven't gotten around to torturing myself like that -- dull mind, heavy limbs, no emotion, repetitive thoughts, the aches and pains from the previous day, and then having to really concentrate just to do simple things and having to really focus your attention off the aching feeling... torture.
Still it seems possible to me and might be an opportunity to change the way you think. You get less sleep, the next day your brain let habits slip away... sounds like that could be a good thing to use to make some changes maybe.
Oh yes... with little sleep you get the fun of actually staggering around and bumping into things because you're a little off balance. "The door jamb jumped out at me! Darn it!"
You can get a lot more work done, but you might not be around to be conscious of that. "Is it fall already? 2005?!"
Everything I see says sleep is important for your brain to repair and organize itself. While you're in la-la land, the parts of the brain you use during conscious thought are getting fixed up for the next day.