Silvanus said:
I think that during a working week, I don't really get enough sleep (about 6.5 hours a day, 7 if I'm lucky, and then more when I'm off the next day).
It doesn't impair my ability to work, and I don't need nearly as much caffeine as some people do. Mostly, it just saps my energy and makes physical exertion difficult.
Sleep need varies from person to person. Adults will usually be in the range 6-9h per day, with most 7-8h. I would suggest anyone regularly getting under 5h a day or needing over 10h may have an underlying medical problem. Anyone who tells you they only need 4h sleep a day is full of shit - at best, if they really are, they'll be operating way below maximum. If you regularly sleep 6.5-7h but tend to sleep more when not busy, that suggests when you're working you're getting a little on the low side. Obviously, we can take less sleep for short periods - it's perfectly normal to under-sleep during the working week and catch up at the weekend, for instance, although it will lead to tiredness by the end of the week.
You can of course change that and alter your routine to get to sleep earlier, and there are all sorts of techniques and "sleep hygiene" processes to help. In practice, most people simply prefer the way they do it, because there are computer games, socialising, TV etc. that they want to do rather than get an extra hour of sleep by going to bed earlier. What certainly would be a problem is insomnia - going to bed and not getting to sleep.
I don't think the 16h-on 8h-off model of our days is probably what we evolved to do. I suspect humans slept - or intensely relaxed - during the day, probably midday - early afternoon, much like the Spanish siesta. There is a "blip" in the circadian rhythm of reduced wake drive around this point.
That's what I remember from studying psychology in school, too. I think the runner up was 9 days, and for some reason, they were worse off than the one who stayed up for 11.
IIRC, the 9-day stint person started having severe hallucinations and paranoia and such.
Yes, they very likely would. Chances are they were also suffering stuff like random neuropathic pain and cardiovascular (usually vasoconstrictive) abnormalities as well. There may be all sorts of variations in how people handle lack of sleep; genetics, general fitness, levels of activity during sleeplessness, etc. If they're chugging caffeine like crazy /andor other stimulants as well, I can see why in a few occasions people just drop dead.
