Burn out or f...f...f...fade away?

Recently, I've been falling asleep relatively late. Now, this might be because it's the school holidays and I've been revising well into the night for my upcoming A-Level exams (Only a month and a half to go!), it might be because I'm worried about the election result, or it might be the beginning of a relapse of the Chronic Fatigue Syndrome I had last [school] year (although I doubt it). At any rate, it's given me plenty of time to think (and to write weird stories about the night and floods and stuff). You're often told that sleeping longer (or at least the right length of time) lengthens your life - or maybe it's the reverse, sleeping too little shortens your life - but I've been wondering just how true that is. You see, it might take years off your lifespan, but do you spend less time 'living'. For the purposes of this thought experiment, we'll take 'living' to mean 'consciously experiencing life'. In order to 'consciously experience life' you have to be awake - for the purposes of this I'm discounting vivid dreams as an example of 'consciously experiencing life', although that is debatable.

Some simple arithmetic shows that if you are awake 18 hours a day (6 hours sleep), but only live to be 70 (which in the context of the 21st century is not all that old), you will be awake for 459900 (18x365x70) hours (I'm ignoring childhood and leap years- too messy, and anyway, a bit irrelevent for these purposes). To equal that on 9 hours sleep a night (15 waking hours a day), you would have to live to be 84. That's 14 extra years, but no extra 'living'.

Now suppose you're awake for 20 hours a day (only 4 hours sleep) but only live to be 60, you will have lived for 438000 waking hours. To equal that on 15 waking (9 sleeping) hours a day, you would have to live to be 80. That's 20 years, without any extra living.

The next question is, what kind of quality of life can you have on 4 hours of sleep a night? I'm no health expert, but I have staffed a camp where we only got 4 hours sleep a night and it wasn't pretty, but I'd imagine your body would adjust. Also consider that you are likely to experience more pain in the twenty extra years (through illnesses, the death of loved ones etc). Maybe I'm just clutching at straws, but I find it somewhat comforting at 1am.

PS Thanks to everyone who listened to my Pause for Thought - well, I'm sure someone listened. Maybe I'll post a recording, if I can work out how to do it.