There is a strong chance I will have to do kind of a difficult military training course this summer to get promoted. I can manage my fitness, but am concerned with the lack of sleep. I am old - well older - when compared to the others going on this training, and will be one of the few females.
I like to sleep, but want to be able to keep up. I am a migraineur, so this has to be managed - but can it be done? I have googles, but got a variety of responses.
What say you, Dopers?
The boss I had for my work-study job in college did it. He operated quite well on 4 hours of sleep a night.
Here’s how he explained it to me:
He served in the Navy during WWII, and rarely got more than 6 hours of sleep a night. After he was discharged, he started thinking, “time spent sleeping is time wasted when I could be doing something. I know I need some sleep, but I wonder how little I can get away with, and still be functional.”
So, he started generally experimenting. He was already accustomed to 6 hours of sleep, so he cut back to 5:45 for a few weeks, and didn’t notice any problems. He then cut back to 5:30, and repeated the process. He kept this up until he was down to 4 hours per night…at that point, he decided that any less than that was somehow flirting with disaster, and so, he stopped with 4 hours.
When I worked for him, he was in his late 50s / early 60s. His routine was that he and his wife would watch the first half of The Tonight Show, and then go to bed (11pm Central time). He’d wake up at 3am, head down to his den (in the basement of his house), and work for 3 hours. His wife would get up at 6am, they’d have breakfast together, and then he’d head into the office, getting there by 8am (but already having worked 3 hours that day).
Now, I should point out that the man also consumed vast quantities of coffee, and was a chain smoker, both of which may have had something to do with being awake 20 hours per day. 
I find that my need for sleep is greatly reduced since I started limiting total carbohydrates and eating more protein, fat, and vegetables. Also I exercise quite a bit. I still give myself 6-7 hours a night because I feel it’s healthiest, but I have no troubles/lack of energy living on 3 or 4 (at least for the relatively short time I have experimented with sleeping less).
I have been working on this, so this may help.
Anecdotical: physical (aerobic) fitness does seem to have an impact. When I was BMI 39 and took the lift for one floor I was much more sleepy at work after 9 hrs sleep than now at BMI 24.5, running half marathons now and then, after 7 hours of sleep.
So embarrassing! Thanks for finding it for me!
Anecdotal information:
A colleague of mine said he used to just get about 5 hours of sleep every night, so he could get more done. He thought he was doing just fine, until for some reason he slept about 8 hours a night for a few nights. After that, he realized just how awesome he felt with a full night of sleep. So now he sleeps about 8 hours.
Non-anecdotal information (warning, I am not even close to an expert on the subject)
I’ve never heard of any studies showing you can live with substantially less sleep. In fact, everything I read seems to confirm how important a full night’s sleep is. So, just sleep however much your body wants you to sleep.
Anecdotally, I’ve trained myself to get by on four hours or so (it’s 2AM at the time of posting this. I will retire shortly. My alarm clock is set for 6). If I sleep for more than about 6 hours, I feel terrible the next day - I’ll be sluggish and headachy all day.
However, I’ve heard experts say that the amount of sleep an individual needs is not really malleable in the long term, but I think it’s true that the amount of sleep any given person truly needs is not universal, so maybe those lucky people who manage to shorten their sleep always had the potential to be able to do it anyway - and maybe some people simply cannot do it without becoming unwell.
I’ve also noted since feeling better and being able to sleep much less (before lifestyle changes and health improvements, I was sleeping 8-15 hours out of every 24) that too much sleep makes me ill… sometimes for hours the next day. The cut-off for me is 8 hours, more than that and I wake with a headache, body pains, lethargy, typical ‘hungover’ feeling. Needless to say I am very careful not to get too much sleep these days.
Wow. I’ve been saying that about oversleeping forever, and everyone in my family thinks I’m weird. But I find the worst symptom is feeling tired. You want to go to sleep, but you can’t, because that will only make things worse.
I once went 4 days straight on 3.5 hours per night. It’s a strange feeling…like you’re not exactly in your own body. It’s like, if you let it, sleep will just take over and you’ll keel over on the spot, so you have to vigilant against it. I hope I never have to do that again.
I don’t feel like that when I sleep less than usual, only when over 24 hours with no sleep at all. Even 1 hour of sleep is enough to prevent that feeling.
The only side-effects I’ve noticed from sleeping 4 hours or less nightly is a]sleepiness earlier in the evening than my usual bedtime (typically I go all day and climb into bed at night feeling wide-awake and alert, but fall asleep very quickly once I’m lying in a dark room) and b]an increased desire to go back and get more sleep when I am getting up in the morning. Both are easily overcome and I feel totally normal otherwise.