I'm 25 and I require 8.5 hours of good sleep for optimal performance.

I did some benchmarking about three years ago by timing myself trying to solve similarly-challenging Sudoku puzzles in a Nintendo DS game. With good sleep, I'd consistently approach 14 minutes with zero mistakes. After about 2-3 days of not having good sleep, it would drop to 16-20 minutes with more mistakes. I would also consciously notice various effects like diminished memory recall, more stuttering, poor focus, etc.

I've also been hearing that the length of sleep required is typically reduced with age. I don't have any citation on this though, would love to read more on the topic if anyone has more insight.

Did you track your performance beyond 8.5 hours?

I didn't focus on that but anecdotally I find that consistently oversleeping (over 9 hours) would leave me groggy and generally reduced performance (at least temporarily in the morning) but not as bad as sleep deprivation. Whereas getting one or two nights of mild oversleeping after being sleep deprived for several days does seem to speed up the recovery time.

Of course there were many other variables like exercise, diet, health, and mood, where each seems to have some minor effect on my sleep requirements one way or the other. The Sudoku benchmarking was performed on more or less "idling" lifestyle (no unusual healthy or unhealthy activities, and I wasn't consuming alcohol/caffeine or smoking).

9 hours of sleep followed by 18 hours of being awake (instead of 8 + 16) is comfortable for me. Unfortunately, it means your personal day keeps shifting relative to most other people's.

If you stretch that slightly into 9+19 you can get 6x28 hour days in a week. That way you can have your weekends in sync all the time.

There is an xkcd strip for this: http://xkcd.com/320/

I always thought that it was a joke, but you can seriously try it and tell us how did it work.

Is anyone actually living with this? [1] A circadian rhythm of 28 hours sounds quite rare.

1: http://www.dbeat.com/28/

I did that for most of a 4 month period and several other smaller stretches about 15 years ago. It worked great for me at a time.

As I've gotten older, it's become easy to fall asleep and wake up when I want to. Two things are critical to that:

1) no screen time in the 2 hours before bed. No TV, no computer. The only exception is reading books on my phone in night mode at the lowest setting.

2) no caffeine except for small amounts of chocolate.

My wife teases me because I can fall asleep in under a minute, and taking more than 10 minutes to fall asleep is actually one of the signs of a sleep disorder. (I don't have any of the other signs). It's not normal, but no TV or computer at night and no caffeine are not normal, either.

I did it for a few months while writing up my Ph.D., and I wish I could continue, but various commitments mean I'm stuck with 7x24. 6x28 suited me very well, felt much better than I do on 7x24.

Cool! Have you tried free running sleep to measure your natural circadian rhythm? [1,2]

1: http://en.wikipedia.org/wiki/Free-running_sleep

2: http://www.supermemo.com/articles/sleep.htm#Free running sleep

Haven't got the chance - would love to do so. No blocks of two weeks without fixed time commitments.

I live with something approximately close.

Having an office to go into and coworkers to be accountable to is the only thing that keeps me sane.

Sort of. I sleep for 9 hours if I've been up for more than about 14 hours prior and there's no alarm. If I've been awake for more than 24 hours it goes up to 12hrs.

If I've had several drinks (alcohol), I never sleep for 9 hrs, it's always less, but I haven't tracked post-alcohol sleep times closely enough to notice if it's still a multiple of 3.

However, I can also do 6 hrs or 3 hrs, and I don't feel groggy but I'll get tired sooner the next night. Not adhering to a multiple of 3 hrs (rem cycles I assume), or reasonably close to that, ends up badly.

What I really need is an alarm hooked up to a primitive EEG so that it can start the clock when I fall asleep, and set off an alarm after a programmable number of minutes. That way I could sleep for 6 hrs without ever being groggy. But even the cheapest EEG stuff I've seen connectable to a computer is not cheap.

> What I really need is an alarm hooked up to a primitive EEG so that it can start the clock when I fall asleep, and set off an alarm after a programmable number of minutes. That way I could sleep for 6 hrs without ever being groggy. But even the cheapest EEG stuff I've seen connectable to a computer is not cheap.

There are various devices for sleep enhancement, e.g. "the sleep watch"[1]. I haven't tested any of them, though (nobody ships stuff to Russia).

[1] http://www.thesleepwatch.com/estore.html

Not cheap, but not really expensive. And, I can attest it has worked flawlessly for me.

It's nice not waking up groggy because my alarm is timed to my EEGs.

http://www.myzeo.com/

Bummer that it requires a headband. Has anyone had success with Wakemate?

http://wakemate.com

I don't worry about a particular number of hours.

Being able open your eyes, refreshed, some time early in the morning, without the need for any alarm, is as good as it gets. This is well within reach if you don't have any dependants.

I need to get back to that. I feel so much worse without it.

I've been doing the same, it's been really helpful. My wife has been very patient with me through this. Any day I get up before I feel like I'm ready, my sharpness and work endurance is substantially worse.

I had the same problem (actually ten hours) until I was 27. It made my academically-rigorous engineering school an extreme challenge. But then I was able to get by with 8 and now 7, which makes things a lot better. No idea why.

29 and the same here. If wake up after 8 I will just be in zombie mode for an hour.

I figured that I need at least 9 hours of sleep to function properly. I'm 34 and I think I always needed to sleep that much.

When I undersleep, I struggle to oversleep. It is hard, but needed anyway.

Yep, true for me too, unless I self-medicate with nootropics, less than 9 hours don't do it for me.

Have you experimented 9 hours of sleep + nootropics?

I meant that with modafinil, I can feel well rested and alert without nine hours of sleep per day; At least for a few days