Sleep patterns. Nature or Nurture?

[Gemini]

[...]

Much like the experience of Wehr's subjects, these references describe a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.

[...]

Holy crap, I'm actually normal?

[vorlon13]

well, without considering fitting in so well at this forum . . . .

[TheRealJoeFish]

My understanding was that, in studies where they basically didn't let people look at the time for a week or two there was a tendency to drift towards longer day cycles of something like 27 hours. I'll see if I can find anything on that.

Another thing to note: have any of you seen those commercials for... I forget what it's called, Natural24 or something like that? They bring up a good point: a number of blind people have trouble syncing their waking/sleep schedules with the solar cycle in the absence of visual light/dark cues. EDIT: This sort of thing also appears to be a rather major problem for international airline pilots too. Essentially, it seems as though the 24-hour cycle is programmed into the human body (inasmuch as the brain and other systems are generally optimized for such a cycle) but the body is reliant on external cues to moderate that cycle. When those cues are disrupted, it results in difficulty.

Edited AGAIN to add: Wikipedia Article on Non-24, the sleep disorder I was referring to above. This includes what is generally considered to be the specific mechanism: Essentially, the day-night cycle is regulated by the pituitary gland, which left to its own devices (ie in the absence of sunlight) averages about 24.2 hours (though it's highly variable and can easily drift up or down). Normally, the sun rising every morning resets the pituitary cycle, hastening the start of the cycle if sunlight occurs before the pituitary gland has started on its own (or, similarly, darkness delaying the start of the pituitary gland is running ahead). In people who either 1) do not observe day/night differences or 2) observe day/night differences in irregular or non-circadian (that is, non-24 hour) ways, there is no proper external regulation of the pituitary gland, and that can result in, for example, a blind person's "natural" wake up time being pushed back an hour every day, which can ibviously severely disrupt social and professional life.

[vorlon13]

My understanding was that, in studies where they basically didn't let people look at the time for a week or two there was a tendency to drift towards longer day cycles of something like 27 hours. I'll see if I can find anything on that.

Another thing to note: have any of you seen those commercials for... I forget what it's called, Natural24 or something like that? They bring up a good point: a number of blind people have trouble syncing their waking/sleep schedules with the solar cycle in the absence of visual light/dark cues.

Still, when the pair of rovers were sent to Mars some years ago, the project scientists went on 'Mars Time' to maximize science return from the mission.  Staying synchronized to the day/night pattern on Mars, while controlling their rovers from earth was anticipated to be 'doable' and very efficient use of the rovers (assumed) limited lifespans. The mission personnel even had special wrist watches made that ticked out 'Martian' seconds, minutes and hours'.

Guess what ?

It turned out to be VERY difficult for them, even though the Martian day is less than an hour longer than an earth day, and everyone thinking it would be a snap to both stay up later every 'night' and get up 'later' every 'day', being so relentlessly out of sync with 'earth' time turned out to be a really taxing ordeal.

[TheRealJoeFish]

My understanding was that, in studies where they basically didn't let people look at the time for a week or two there was a tendency to drift towards longer day cycles of something like 27 hours. I'll see if I can find anything on that.

Another thing to note: have any of you seen those commercials for... I forget what it's called, Natural24 or something like that? They bring up a good point: a number of blind people have trouble syncing their waking/sleep schedules with the solar cycle in the absence of visual light/dark cues.

Still, when the pair of rovers were sent to Mars some years ago, the project scientists went on 'Mars Time' to maximize science return from the mission.  Staying synchronized to the day/night pattern on Mars, while controlling their rovers from earth was anticipated to be 'doable' and very efficient use of the rovers (assumed) limited lifespans. The mission personnel even had special wrist watches made that ticked out 'Martian' seconds, minutes and hours'.

Guess what ?

It turned out to be VERY difficult for them, even though the Martian day is less than an hour longer than an earth day, and everyone thinking it would be a snap to both stay up later every 'night' and get up 'later' every 'day', being so relentlessly out of sync with 'earth' time turned out to be a really taxing ordeal.

I hadn't updated my post when you quoted this, but see above; I guess I would argue that the research suggests if they were *on mars*, where the sun actually did come up every 25 hours, it would've been the most natural thing in the world. But on earth, with the sun on the 24-hour cycle, the only ways to get off of that are *seriously* mess up your brain, or not observe the sun at all.

[vorlon13]

Might be a factor. Although until Elon Musk gets a crew there (assuming China allows them to set down) we won't know for sure.

[ignoramus]

Holy crap, I'm actually normal?

Hey, let's not get carried away now!

[Losty]

Please tell me those hibernating people at least got up to use the restroom?

[Jackalope]

I remember hearing somewhere that we originally could have slept every other day (our species or our ancestors), but we ended up settling into a daily routine instead.

No idea where that came from or how reliable it is.

My money somewhen near the start of agriculture.

[Jackalope]

I can't see any evolutionary benefit to that one though Rob?  Was it theorised in a doco or something?
Be aware and awake during the day seems the most beneficial?

Sure it could. If you as a hunter-gatherer needed to hunt and gather efficiently to sock away winter stores, there's definitely an advantage to being able to stay up - you can stay on your prey or on foraging that much longer.