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theUturn2Yz t1_iswqedt wrote

I hope someone can chime in if they know of any species of animals that historically hibernate during winter and become active during the summer in the Artic Circle where the sun does not set for weeks. Maybe an expert can also talk about nomadic cultures in a similar context.

A quick tangent: there is a psych study where participants willingly were placed in an artificial residence (possibly in a building or underground) and left inside for months without the ability to tell what time of day it was from external stimuli. Basically, humans (and I would assume almost all animals) have an internal circadian clock that regulates bodily functions. For some odd reason, ours tends to run around 25 hours per day (not 24).

Also, there are examples of cultures predominately taking naps or socializing at various times of day contrasted to other cultures e.g. Spain and Turkey. Old people start to sleep at odd hours and sometimes require less sleep too.

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Upset-Ad4844 t1_iswrmb3 wrote

Here is a link to an article about the study you mentioned. The abstract is fairly easy to understand.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1330995/

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que_la_fuck t1_it0sape wrote

I just read a little of this. I find it fascinating that 2 subjects ended up on a 32hr cycle with alternating 8hr and 16hr sleeps and 24ish hours awake and active. Now this might sound too crazy, in fact, sounds like a fun weekend, but they thought they were awake and sleeping their normal amount.

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Menirz t1_it10qv1 wrote

Not too surprising to me, since I have a strong suspicion that I'd end up just like them if I was in a similar study.

When not actively trying to maintain a schedule, I'll tend to sleep for about 12 hours and be awake for about 20 hours. Makes it a pain in the ass to keep a normal schedule without constant alarms and reminders.

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Menirz t1_it10rde wrote

Not too surprising to me, since I have a strong suspicion that I'd end up just like them if I was in a similar study.

When not actively trying to maintain a schedule, I'll tend to sleep for about 12 hours and be awake for about 20 hours. Makes it a pain in the ass to keep a normal schedule without constant alarms and reminders.

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redmonkees t1_isyfigg wrote

Our Human circadian system (and most vertebrates and many inverts, though often through different biological mechanisms) is completely governed by light availability. Light presence degrades a protein that is a part of our circadian “clock”, and sets a rhythm that tells us to sleep. You can set a circadian rhythm in humans with just an hour of light exposure at the beginning and end of the day time. Interestingly, hibernation and different types of torpor (prolonged moments of rest) are totally unlinked to the circadian system, which solely governs our sleep based on the position of sun in the sky/daylight. When you think about it, that makes sense - they often go into burrows, where sunlight reaches very little. Hibernation is actually more so linked to cold; though whether that’s a direct link to cold or a result of decreased nutrient availability varies between species. It been shown that some species at the very least actually are able to complete shut down their circadian system from functioning during hibernation to prevent interference with the two systems.

A really interesting part of animal life in the arctic circle though is that not all species hibernate. Arctic reindeer, which don’t hibernate, have been observed to have a much less controlling circadian system compared to closely related, non arctic species. They’ve essentially shut off their circadian system as an adaptation to maintain essential biological needs throughout the day. They are able to graze periodically every few hours throughout the day as their body needs, even without the presence of sunlight. They do still have higher prevalence of melatonin during the night, which indicates that they can still denote when the seasons change, but it’s not linked to a distinct sleep period, unlike other ruminates. Unfortunately, that is an adaptation to the environment that would take generations and generations to arise in a species randomly, and as humans are relatively new to the arctic environment in an evolutionary sense, that adaptation has not been observed yet in native human populations of the arctic. Humans are still beholden to the circadian system in the arctic, meaning that in periods of full dark there is more pressure to sleep in a free running period of 25 hours.

Also, because is was mentioned, the 25 hour free running period you spoke of (free running means the natural period of sleep observed in no-light conditions) is something that has been observed in many species. It’s not actually odd like you said, because when you arrive at the mechanic behind it the answer makes sense. The link is that it’s only present in diurnal (active during the day) species. Nocturnal species tend to have a 23 hour free running period. Because the protein that signals sleep degrades in light, and that degradation takes time, this allows diurnal and nocturnal animals to be awake at the right time when entrained to the sunlight, sometime around daybreak and sometime after sunset respectively. Theoretically in some exoplanet that might have a 20 hour day, species that evolved there with the same circadian rhythms would have a 21 and 19 hour free running period because of that.

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slacker346 t1_isyv8wu wrote

Wikipedia is a little light on the exact source, but they make the claim that the 25 hour study was flawed, in that it allowed artificial light. If I'm to believe their references, a better estimate for human circadian rhythm is 24h11m. And it varies by gender.

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smcarre t1_it09y52 wrote

I mean the alternative is having the subjects spend days in complete darkness.

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Polikosaurio t1_iszg77a wrote

Its weird but foreign people mocking us spanish for taking naps made me cut them out entirely. Such irony that siesta is slowly getting common place along cultures due to climate change. This past summer was so hot that countries that weren't used to such a heat wave started to adopt mid day naps. My point is that climate pays a huge factor aswell.

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dmnhntr86 t1_iszwx4w wrote

>Its weird but foreign people mocking us spanish for taking naps

IDK about the rest of the world, but we Americans have been brainwashed into thinking that working to much and sleeping too little is some kind of virtue. I remember hearing about Mediterranean cultures having a big lunch as their main meal and then having a nap because it's the hottest part of the day, then go finish up the day's work when the sun isn't beating down so hard. I thought it made a lot of sense and I wish it was a thing in the southern US.

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-Hastis- t1_iszohlj wrote

Also do not forget that the older you get, the less your body naturally produce melatonin. Which is one the reasons old people can't sleep as much. It does not necessarely mean that they don't need it. I would even suggest the hypothesis that it create a negative feedback loop that accelerate the aging process as you get older.

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ChipChippersonFan t1_it0yejr wrote

I, for one, wish that I lived on a planet with 27-30 hour long days. I'm a "night person", and every night is a struggle to get to sleep, and every morning is a struggle to wake up. If left to my own devices (ie. if I didn't have a job) I would stay up an hour or 2 later every day and sleep 2 or 3 hours later every morning.

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Gr1pp717 t1_it0wzwh wrote

For a few months when I was 18 or 19 I was utterly ... free. For lack of a better word. No job, no responsibilities. I slept and woke when and for how long I wanted. Was staying in a friend's basement that was pitch black 24/7.

I found that I naturally drifted towards something like 28 up, 12 down. It varied a lot, but was way longer than the normal 16/8 shtick we're stuck with. Also, I never felt more alert and alive before or since.

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Recyclopslady t1_it0r6cn wrote

This just prompted an interesting question in my head, as a recent mother, I was told to make sure to get the baby accustomed to night vs day to help them “develop their circadian rhythm”. So…. What if this study was conducted on humans straight from birth (terrible idea and doubt it would ever be moral to do it); however, would the results be drastically different if a baby never experienced night/day from the beginning?

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ApoptosisPending t1_isz27yj wrote

We have a cluster of cells called the suprachiasmatic nucleus that serves as the internal clock. It’s hard to say whether it’s based on the length of the day because it’s evolved over time with nothing more than a 24hour day. I think OPs question is asking the mechanism of the SCN and it would respond to different period lengths, which has yet to be discovered. If the fundamentals of the internal clock are true, it wouldn’t matter how long the day is because our internal clock is telling time no matter what.

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matts2 t1_iszvg90 wrote

The study misunderstood the results. We have an internal clock. It is about one day long. Then it gets reset. If it doesn't get rest it gets chaotic. It doesn't find a different day, it doesn't find a regularity at all.

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lovegermanshepards t1_it5dpca wrote

That’s super interesting. I’ve always felt like my body was on a 25 hour clock… and every couple days I have to do my own little mini daylight savings time to try to reset back to 24

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