Circadian Clock

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lonestar998
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Circadian Clock

Postby lonestar998 » Mon Mar 04, 2019 9:31 pm UTC

What would be the circadian rythm (biological clock) on mars for a human being traveling to mars vs a human being born on Mars (Evolution? After many generations?)

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gmalivuk
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Re: Circadian Clock

Postby gmalivuk » Tue Mar 05, 2019 4:28 am UTC

Circadian rhythms aren't exactly 24 hours even for species that have evolved on Earth for millions of generations, so I doubt Mars's 30-minute-longer days would have much of an impact, honestly.
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tomandlu
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Re: Circadian Clock

Postby tomandlu » Tue Mar 05, 2019 9:05 am UTC

For real fun and games, read up on Richard Feynman's experience of messing about with day-lengths...
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Eebster the Great
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Re: Circadian Clock

Postby Eebster the Great » Tue Mar 05, 2019 7:06 pm UTC

People on Mars would be living under and around artificial light 24/7 anyway like we do on Earth, but to a greater extent and with a weaker sun. If there were a long-term evolutionary effect on circadian rhythm on Mars, because people with certain rhythms had more successful children than others, I would imagine it would have more to do with social pressures than the extra fifteen minutes of sunlight and of darkness.

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Heimhenge
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Re: Circadian Clock

Postby Heimhenge » Tue Mar 05, 2019 7:46 pm UTC

Totally agree with ETG. Despite the popularity of domed cities in syfy, the colony would likely be underground, maybe in a lava tube. Anything on the surface would be mostly a metal shell with maybe a small window. All would need artificial lighting, and the occupants would be mostly oblivious to the day/night cycle. The larger evolutionary change would no doubt be driven by the 0.38g gravity.

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Re: Circadian Clock

Postby Soupspoon » Wed Mar 06, 2019 4:47 am UTC

Unless the colony was created to copy the clock of the coloniser¹, in a direct reversal of rover-operating teams adhering to a schedule of Martian 'sols' despite themselvs being Earth-based, or similarly designed around a military/submarine-like hot-bedding shift pattern² tied to Earth cycles then I would imagine that (regardless of visual exposure to the outer surface) there'd be no issue with the logical following of Sol cycles, even in their subarean caverns, with any proper and unanacrhic devotion/submission to routine resetting the "free running period" of otherwise healthy people to the 24h and a smidgen less than 40 minutes of the planet's appropriate rotation.

NASA experiments have established that a 24.65 hour (24'39") cycle is adaptable to, I imagine this was directly with a future Mars in mind (or the aforementioned current rover-drivers), but my source for that doesn't actually elaborate why they tried it. That value (and the lower-end they tested, sub-24) also could be tied to convenient integer numbers of orbits per 'day' of the ISS (though at the current 92ish minute cycle it adheres to somewhat straddles the given values, and with a superfluity of sunsets and sunrises anyway, they just stick to 24 hours (based on UTC, I think, checking the general distribution of children mbined sleep times).

Lunar colonies would be interesting. Around fourteen Earth days each of day and night, like a rapidly advanced version of a polar research station's experience of long periods of day (in the respective summer) and night (respective winter) might benefit from the experiences of Amundsen-Scott/Kunlun/Vostok Stations' personnel and administration. And all near-side stations having a basically permanent (though phasing, could be significantly bright) Earth in the sky whenever they afford themselves an outside view. Or it's popping over and under the horizon in something like the long cycle if you're stationed on either rim. I imagine you'd use an arbitrary Earth-time cycle there, dimming the internal lighting for the adopted 'night', except maybe in the part of any Stepping-Stone base you might have set up future Martian personnel where you could adopt the arean Sols you want to acclimatise them to.


¹ Probably UTC, if international, but Houston or Beijing or Moscow time/etc could be it.
² Just had an interesting read of shift-patterns in use. The US Navy seems to have changed from 18 hour 'days' of 6 hour watches and 2x6 of other duties and sleep (which must have played hell with everybody!) to 3x8s=24, albeit with progressing cycling of duty watches/offs/rests per system due to coprimality between the dividing components. The RN system(s) often incorporating dog-watches shows a different approach, apparently quite successful.

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Eebster the Great
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Re: Circadian Clock

Postby Eebster the Great » Wed Mar 06, 2019 8:29 pm UTC

You can of course adapt to 24.65 hour days, because you can quite easily adapt to 28 hour days. It's probably true that schedules on Mars would be based on the length of the Martian sol, which is fine, because that's almost identical to the length of an Earth day. People's circadian cycles already vary greatly, and the cycle duration would only change at a genetic level due to natural selection. So the question is if your circadian rhythm would affect your reproductive success. On Earth, it doesn't seem to affect it enough for stabilizing selection to keep everyone, or indeed anyone, on a 24 hour schedule without the sun for reference. I can't imagine it would be so different on Mars.

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Re: Circadian Clock

Postby ijuin » Wed Mar 06, 2019 9:02 pm UTC

Of additional interest would be how people deal with the cycle of religious observances, especially if they insist upon synchronizing it with Earth schedules.

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Soupspoon
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Re: Circadian Clock

Postby Soupspoon » Wed Mar 06, 2019 9:51 pm UTC

On that last point, in the book Wheelers (an Ian Stewart and Jack Cohen book in part regarding the first contact between humans and jovians) an order or Tibetan monks now inhabiting a hollowed-out asteroid belt have had to deal with how they observe rituals relating to when the Sun passes above a certain sacred Earthly peak, when they're not just not in Tibet, but not on Earth to 'easily' extrapolate "when it would theoretically rise if you could imagine away the curvature of the Earth between".

They have adapted to their current situation where relative orbital (and orbital plane) juxtapositions are fully accounted for, IIRC.

I can't get to my copy of the book right now. And it's drifting the subject a bit, so that's probably for the best.

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Re: Circadian Clock

Postby p1t1o » Thu Mar 07, 2019 11:27 am UTC

Its possible to adapt to a 4 hour cycle even, its call "The Uberman" and is extremely difficult to get into, but once you are in for a few weeks, it become natural. Based on 20 minute naps every 3-4 hours it allegedly allows you to rest sufficiently on a minimum of sleep, unlocking hours of wakefulness you didnt have before. If you can overcome the "zombie phase" that is. Its actually quite interesting.

https://www.polyphasicsociety.com/polyp ... uberman-2/

I think the circadian rhythm appears quite malleable, but sleep itself fascinates me because we die without it and it is so prevalent in the animal kingdom despite huge evolutionary pressure.

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Re: Circadian Clock

Postby gmalivuk » Thu Mar 07, 2019 6:43 pm UTC

That page says "the body gets different types of sleep at different times of the day", which means it's not a true 4-hour cycle, it's a 24h cycle with multiple bits of sleep instead of one long sleep.
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Soupspoon
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Re: Circadian Clock

Postby Soupspoon » Thu Mar 07, 2019 7:25 pm UTC

When being crepuscular is not felexible enough for you, go for full cathemerality!

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Heimhenge
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Re: Circadian Clock

Postby Heimhenge » Thu Mar 07, 2019 8:45 pm UTC

I have on many occasions (most often prompted by a computer crash) "flipped" my sleep schedule from 6 hours at night to staying up all night to fix the problem, then sleeping during the day. I can gradually ease out of it and get re-synced with my wife's sleep schedule, but it takes a few days. I don't do this unless I have to since it's not a pleasant experience.

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Re: Circadian Clock

Postby Soupspoon » Fri Mar 08, 2019 4:34 am UTC

After ecstatically leaving a job once, and temporarily then having the time to spare that it had not afforded me, I spent a couple of months basically doing this (only it was well before that*) such that pre-existing weekend commitments would fit around an almost-normal section of the cycle but I could spend a lot more time on personal things without so many breaks. But it was a difficult alteration to come out of, for my next stint of employment, I recall. Bad habits meant (at least notional) black marks that I had to erase by visibly proving my worth a bit more than maybe I otherwise would have had to (preferring, as I do, to just get on with things and not make a fuss).

To be honest, I've always been shifted towards late to rise and late to bed, useful when (here in the UK) I've had to liaise with west-coast US people. And right now I'm clearly demonstrating this willingness/ability by it being 04:25am and I've just come here after finishing my 'daytime' tasks in my current vocation. (With upcoming Saturday sporting commitments already built into my schedule, but I've still to work out how Sunday needs to go to get me properly (un)synched by Monday.)

* Which was, ooh, a nice roundish 1800 comics ago, or 600 weeks, so approx 11.5 years ago, without breaking out Zeller's Algorithm or actually looking it up. Doesn't time fly? I don't think I was even lurking on the fora/wiki back then, though, so probably never ever got to "GOOMHR" that one.

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Re: Circadian Clock

Postby p1t1o » Fri Mar 08, 2019 9:43 am UTC

gmalivuk wrote:That page says "the body gets different types of sleep at different times of the day", which means it's not a true 4-hour cycle, it's a 24h cycle with multiple bits of sleep instead of one long sleep.


It'd still work well if your planet had a 4hr day ;)

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Re: Circadian Clock

Postby Heimhenge » Fri Mar 08, 2019 11:55 pm UTC

And if you go so far out that the Sun is just a bright star, say a mining colony on Ultima Thule or other KBO, your day may as well be a standard 24 hour cycle regardless of rotation period.


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