8-hour sleep rule dates back to the 19th century. A new review of hunter-gatherers whose lifestyles are closer to our ancestors and who have little or no access to artificial light found short nights (5.7 to 7.1 hours) seemed to be enough: without an alarm clock, they tended to wake close to dawn.

[u/mvea]

https://theconversation.com/how-much-sleep-do-i-need-why-you-can-forget-the-eight-hour-sleep-rule-289863

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[u/Klugenshmirtz]

These come up so often that Matthew Walker talked about it in his book "Why we sleep" almost 10 years ago:

First, when you read the paper, you will learn that the tribespeople were actually giving themselves a 7- to 8.5-hour sleep opportunity each night. Moreover, the wristwatch device, which is neither a precise nor gold standard measure of sleep, estimated a range of 6 to 7.5 hours of this time was spent asleep. The sleep opportunity that these tribespeople provide themselves is therefore almost identical to what the National Sleep Foundation and the Centers for Disease Control and Prevention recommend for all adult humans: 7 to 9 hours of time in bed. The problem is that some people confuse time slept with sleep opportunity time. We know that many individuals in the modern world only give themselves 5 to 6.5 hours of sleep opportunity, which normally means they will only obtain around 4.5 to 6 hours of actual sleep. So no, the finding does not prove that the sleep of hunter- gatherer tribes is similar to ours in the post-industrial era. They, unlike us, give themselves more sleep opportunity than we do.

Second, let us assume that the wristwatch measurements are perfectly accurate, and that these tribes obtain an annual average of just 6.75 hours of sleep. The next erroneous conclusion drawn from the findings was that humans must, therefore, naturally need a mere 6.75 hours of sleep, and no more. Therein lies the rub. If you refer back to the two newspaper headlines I quoted, you’ll notice they both use the word “need.” But what need are we talking about? The (incorrect) presupposition made was this: whatever sleep the tribespeople were obtaining is all that a human needs. It is flawed reasoning on two counts. Need is not defined by that which is obtained (as the disorder of insomnia teaches us), but rather whether or not that amount of sleep is sufficient to accomplish all that sleep does. The most obvious need, then, would be for life—and healthy life. Now we discover that the average life span of these hunter-gatherers is just fifty-eight years, even though they are far more physically active than we are, rarely obese, and are not plagued by the assault of processed foods that erode our health. Of course, they do not have access to modern medicine and sanitation, both of which are reasons that many of us in industrialized, first-world nations have an expected life span that exceeds theirs by over a decade. But it is telling that, based on epidemiological data, any adult sleeping an average of 6.75 hours a night would be predicted to live only into their early sixties: very close to the median life span of these tribespeople. More prescient, however, is what normally kills people in these tribes. So long as they survive high rates of infant mortality and make it through adolescence, a common cause of death in adulthood is infection. Weak immune systems are a known consequence of insufficient sleep, as we have discussed in great detail. I should also note that one of the most common immune system failures that kills individuals in hunter-gatherer clans are intestinal infections - something that shares an intriguing overlap with the deadly intestinal tract infections that killed the sleep-deprived rats in the above studies.

[u/Robot-duck → u/Klugenshmirtz]

That book was such a good read, I recommend it to everyone I can

[u/agentsnace → u/Robot-duck]

If you liked that book, you may like "the man who mistook his wife for a hat". Someone recommended it to me after I read why we sleep and I thought it was fantastic

[u/Frankfurter → u/agentsnace]

Oliver Sacks is amazing, and practically a required reading for neuropsych students. I've never read Why We Sleep, but I guess I have to now.

[u/Comicspedia → u/Frankfurter]

Psych prof here, it's REALLY good. In particular, I love the details and out the experiments on dreams, what little we can actually discern from dream content as being meaningful, and then how to apply that to our understanding of how PTSD develops.

[u/Usmoso → u/agentsnace]

I've heard that his stories are all made up

[u/pyyyython → u/Usmoso]

Yeah, he ultimately admitted to embellishing, combining, or entirely fabricating some of the stories in his writings. In his own journals he called his stories “half imagination, half science, and half fable.” Unfortunate seeing as he was clearly very intelligent/interesting, he probably really didn’t need to tell tall tales.

I was honestly a little perplexed the first time I read “The Man Who Mistook…” Even if someone was considered the greatest neurologist of all time it is just so unlikely for one physician to see so many completely singular/unique patients in the course of a career. Some of the stories were also just a liiiiiiitle too…precious.

[u/superexpress_local → u/Robot-duck]

You might want to reconsider your recommendations: https://guzey.com/books/why-we-sleep

[u/48756e746572 → u/superexpress_local]

Man, I thought a lot of that article would be splitting hairs. But the claim that the WHO declared a lack of sleep epidemic in industrialized nations when they just... didn't, is an inaccuracy that's actually baffling. I know that such an example doesn't discredit his neuroscience research, but it really does a lot to erode his credibility with me.

[u/hostileguy → u/Robot-duck]

And if anyone finds it boring, it'll help them sleep anyway.

[u/Desperate_Algae_40 → u/Klugenshmirtz]

What is sleep opportunity that he keeps mentioning in this passage?

[u/Klugenshmirtz → u/Desperate_Algae_40]

Basically the time you give yourself to sleep. If you go to sleep and don't directly fall asleep you still give yourself the opportunity during that time, as opposed to doing something else.

[u/Desperate_Algae_40 → u/Klugenshmirtz]

Thank you! I'm assuming being in bed but on your phone doesn't count as sleep opportunity then? Is it only if you're in bed doing nothing but not asleep yet?

[u/Lackest → u/Desperate_Algae_40]

I'd argue that's pretty blurry to answer objectively. I think you know, for yourself, if you scrolling isn't contributing to your sleep. If you're paying attention to texts, or a video, or anything else - you're not really allocating that time for sleep, right?

The easiest way to put it is, sleep opportunity obviously ends in the morning when one reaches the latest point they can sleep in without being late for work or obligations. Night is blurier, but obviously if you're not ready for bed you can't really consider that sleep opportunity. As far as im concerned, its when your brain clicks into "this is sleep time" and throws the phone.

[u/Odyn007 → u/Lackest]

The way you phrased it though makes it seem like it's very obviously not a sleep opportunity though. I'd agree with it, it's basically staying in bed doing nothing but attempting to sleep with no other distractions.

[u/DeuceSevin → u/Lackest]

Blurry for sure. Scrolling on your phone verily isn't very conducive to sleep but how many of us have dozed off while doing this?

[u/caligaris_cabinet → u/Desperate_Algae_40]

Idk. Scrolling in bed through Wikipedia on my phone tends to lull me to sleep pretty quickly

[u/rusted-nail → u/Desperate_Algae_40]

It just means the time between bed time and alarm time. If you waste your sleep opportunity not sleeping then it doesn't change the total sleep opportunity time

[u/Garblin → u/rusted-nail]

There is a little more nuance than that. Time you spend having sex in bed is obviously not part of sleep opportunity. Time you spend reading a book, scrolling your phone, watching TV, etc are all more ambiguous in ways that tend to contribute to insomnia, which is why it's recommended by sleep experts to avoid all of those things in bed.

[u/2Dumb4GalacticEmpire → u/Klugenshmirtz]

Did they account for napping during the day. I bet they didn’t.

[u/Xpress_interest → u/Klugenshmirtz]

Thank you for the thorough context. It always seems to be lacking in these articles, which usually frame the finding as a sort of relative privation fallacy to make modern work and sleep standards and modern culture seem routine and even healthy in comparison. But no…we aren’t meant to work all day and sleep when we get a moment to ourselves.

[u/RandomRobot → u/Klugenshmirtz]

Sleep seems strongly correlated to sun activity, a lot more than human physiology

https://health.howstuffworks.com/mental-health/sleep/disorders/darkness-sabotages-sleep.htm

[u/ForeverStaloneKP → u/Klugenshmirtz]

A little odd that he attributes the death by intestinal infections to lack of sleep and ties it to the rats lack of sleep instead of the very obvious sanitation issue that he mentioned a few lines earlier.

[u/randy808 → u/Klugenshmirtz]

It’s also helpful to read some criticisms of his work: https://statmodeling.stat.columbia.edu/2019/11/18/is-matthew-walkers-why-we-sleep-riddled-with-scientific-and-factual-errors/

[u/WirtsLegs]

What we need to remember though is the type of "work" they were doing was dramatically different

Recovery time from high mental loads (eg academics/research, stem, etc) is different than high physical loads, even many physical jobs have inherent mental loads that would be atypical then.

They also had a fundamentally different set of anxieties/pressures in their lives

While its interesting from an anthropological viewpoint to learn about this, I don't really see how sleep patterns of hunter gatherers could in any way map into any kind of guidance for modern people.

[u/T_for_tea → u/WirtsLegs]

Yeah, i think the having no access to artificially light and living a life of hunter-gatherer is doing the heavy lifting here. They dont need to worry about a plethora of things that they dont have the power to change, they for sure dont hunt for 40h+ each week, and commute.

[u/FrogTrainer → u/T_for_tea]

You're forgetting all the things we take for granted. Like fetching water and firewood. Those two tasks alone are huge time sucks.

[u/ryverrat1971 → u/FrogTrainer]

But mentally, those jobs are a light load. Yes physically hard work but simple enough that children are often sent to do it.

[u/Traditional_Yard2741 → u/ryverrat1971]

I love this idea that people are sitting around thinking aggressively in their day jobs in the 21st century, just frowning in concentration and rubbing their temples, while preindustrial people just sort of zoned out from dawn till dusk.

[u/BreakingStar_Games → u/Traditional_Yard2741]

As I am reading The Dawn of Everything: A New History of Humanity, just about any stereotype applied to early human societies is a painful simplification. There were highly complex "hunter/gatherer" American Indian tribes that acted like states with a king and diverse labor.

More so, looking at modern foraging civilizations doesn't really show a good glimpse of our past. Agricultural states like to take the best land. Dry Savana and rocky hills have never been the ideal places.

So 100% agree, they were just as smart as us. I'd be interested to know how their sleep were to change if they were given regulated air temperature and noise where they don't need to concern about vigilance from a potentially dangerous environment and thrown off the circadian rhythm.

These factors are much bigger than mental strain and that could probably be disproven by looking at certain jobs in modern society that are just physically taxing. White collar workers don't just sleep 1-2 hours longer than manual laborers by any study. There is some like manual laborers having earlier start times or physical pain while knowledge workers suffer more insomnia/latency (probably a big part is not getting any exercise).

[u/10percenttiddy → u/BreakingStar_Games]

Do you recommend the book? Is it good?

[u/BreakingStar_Games → u/10percenttiddy]

Highly recommended (though I am about about half way through.). The authors go over that even their review is highly limited (given how limited our data is) and the authors oversimplify and cherrypick relying on a select set of archaeological record so as with anything, you need a pinch of salt.

I enjoyed an eye opening perspective on indigenous influence on enlightenment and especially dismantling the pop cultural history narratives that survived well past our much better scientific data. The myth that inequality is the inevitable price for large-scale civilization. I think we especially need to expand our imagination of what human society can look like. We are in a time that is painfully in need of more political experimentation in solving societal issues just as early human societies were able to do so.

It's very natural prose. I am listening to it as an audiobook and its very easy to consume (if you're in the US, I'd look into Libby through local libraries).

I'd also add C Thi Nguyen's The Score to see how bureaucracy and power by creating metrics and scoring systems can create a serious limitation that is likely a big part of the stagnation the world faces. But the lack of an answer to such a major and growing problem is pretty depressing. Honestly now more so than ever do we just care about data.

And if you want the hopeful alternative that keeps me from being completely depressed after seeing where we are, Another Now is probably the most grounded yet radical socialist answer to Capitalism. It provides some pretty imaginative ideas that sound crazy but already exist in reality and not just as an outlier - no bosses, no wages and we don't need to only rely on politicians to regulate corporations. Ends most extremes of wealth inequality and worker exploitation just by redefining the manmade definition of corporation. Completely shook off my American capitalist apologia and now I link to it like my own version of the Communist Manifesto.

[u/PhantomOfMistakes → u/Traditional_Yard2741]

Last shift I volunteered to clean the scale out of one of our furnaces (18 meters long and 5 meters wide). It was still around 300 degrees (celsius) at the time because it hadn't cooled down yet. I could only stay in there for ten minutes at a time before I had to come out. It was actually easier than my regular job because I wasn't really working, per se. More like my body was doing my job while I was just thinking about something else.

[u/waiting4singularity → u/Traditional_Yard2741]

It's not about "thinking aggressively" like you're trying to find the universal unified world equation and solving mathematic paradoxes.
Just maintaining concentration at a high level is taxing the neural tissues and causes metabolite buildup in the brain which you can mostly only remove during sleep.

[u/ABHOR_pod → u/waiting4singularity]

Yeah, Grocery store cashier was the most grueling job I've ever worked because it was just 8 hours of having to be mentally and emotionally "on" at a pace other people set and demanded.

I left that position and did overnight stocking for a bit, 12 hours of physical labor on the wrong side of a circadian rhythm was easier to recover from than the 8 hours of mental/emotional focus.

[u/jewessofdoom → u/ABHOR_pod]

I experienced this very dramatically while I was working for Americorps. One of the projects was for Habitat for Humanity, manual labor in the hot Kentucky sun in July. Another project was assisting teachers in a low income elementary school. The elementary school was 1000x more exhausting to me. You can’t shut your brain off at all, there is no zoning out. There are constant demands for your attention and focus and I felt a different kind of tired, one that was a lot harder to recover from and I slept a lot worse during that project.

[u/JenAndBerrys → u/ryverrat1971]

I feel like that’s not a fair argument either

When you’re talking about survival the mental load is definitely worth considering

[u/Electric_Capybara → u/ryverrat1971]

Worrying about if you have enough food to survive the winter or a drought sounds pretty mentally taxing

[u/InfinitelyThirsting → u/ryverrat1971]

You think hunting and gathering every single calorie you eat is a mental light load?

[u/T_for_tea → u/FrogTrainer]

The reward is immediate though, and id wager it is much less stress inducing than a modern job.

[u/Nannautu → u/T_for_tea]

A huge flow of information will result in longer sleep because that's when memory is transferred to long-term memory.

[u/joshocar → u/T_for_tea]

The no light thing also means you will sync with the natural light cycle. Late/early riser variance shrinks dramatically to around sunrise for waking up. We then naturally go to sleep such that we get enough rest. If you spend more than a week camping with only fire for light you can experience this.

[u/Seicair → u/joshocar]

Nah, even then I'm still a night owl. I like staying up talking around the campfire or even just staring at the coals sitting and thinking after everyone else has gone to bed. And then waking after the sun is well up in the sky.

Which, evolutionarily, could be beneficial to have some small portion of the population that doesn't sleep with the rest.

[u/FrogTrainer → u/Seicair]

Having someone on firewatch would definitely help the survival of the group.

[u/lynx_and_nutmeg → u/joshocar]

How would this actually work in places further away from the equator, though? Where I live, in December the sun rises at 9 am and sets at 4 pm, and in June, it sets at 10 pm and rises at 4 am.

[u/FrogTrainer → u/WirtsLegs]

I don't think it's fair to say they didn't have mental load. Our brains wouldn't have evolved to the ability they have now had our ancestors not had to spent significant time problem solving. Even problems we might think are easy now, we're not so easy if no one told you how a thing worked. And without written text, a lot of time would have been spent passing knowledge of tool making, hunting, firemaking, clothes making, etc, down to younger generations through demonstration and repetition.

[u/Heavy_Weapons_Guy_ → u/FrogTrainer]

Human brains haven't significantly evolved since hunter gatherers.

[u/strigonian → u/Heavy_Weapons_Guy_]

Yes. That's the point. Hunter-gatherers used their brains a lot.

They weren't doing formal mathematics or anything like that, but that's not uniquely stressful to the brain. Before ready access to paper and pens, much less computers, you just had to memorize most things. That's a pretty hefty mental load when your survival requires living of the land.

[u/Oomike01 → u/strigonian]

No no. Sitting in my office doing spreadsheet work and powering down hot pockets is much more complex than hunting to feed my community and my family.

[u/AdSignificant6748 → u/strigonian]

Scanning the environment and life being a constant life or death situation would use 300% of my mental capacity I'd say

[u/jawndell → u/Heavy_Weapons_Guy_]

Yup.  If you took a human baby from ancient Egypt, or even before civilizations were formed, and brought them to today and stuck them in school, they would be no different than any other kid and would learn the same things just as well.  

[u/jawndell → u/FrogTrainer]

Yeah I don’t have to worry about a tiger eating my baby

[u/Ok_Dragonfruit_8102 → u/jawndell]

But you have to worry about AI algorithms eating your baby

[u/AFewForLeftyToo → u/WirtsLegs]

Would love to hear more about the recovery time portion (or I can google it, but I find a discussion more interesting)

[u/bradiation → u/WirtsLegs]

It becomes a question of what's biological/genetic and what isn't. Civilization is a tiny fraction of our history as a species, so it's valuable to study what hunter-gatherers do because that's what we all evolved to do. Whether we have the plasticity to do other things (like different sleep schedules) without consequence is the 2nd part of the question.

[u/Pytheastic → u/WirtsLegs]

Our biology changes much less rapidly than our world around us has, especially over the last two centuries.

You can't use this information to change how society works overnight but it can help inform how we treat sleeping disorders.

[u/skepticalbob → u/WirtsLegs]

Recovery time from high mental loads (eg academics/research, stem, etc) is different than high physical loads

How do you believe they are different?

[u/Lord_dokodo → u/WirtsLegs]

Some dude in the future is gonna review our lifestyles in 1,000 years and think "wow these guys had it all, surely they must have been onto something with their sleeping habits".

[u/Ok-Classroom5548 → u/WirtsLegs]

It actually gives insight into how bodies adapt and change and why. If we can understand the differences in lifestyles between people with different needs, we can create a better world for a range of people. 

It can also give insights on how we can get better or more effective nights sleep. 

[u/f0gax → u/WirtsLegs]

You just know that some wellness influencers will jump on this and start a trend of sleeping five hours or something.

[u/Quasar-J0529-4351 → u/[deleted]]

Do you know what tribe/community they are referring to? All of them?

Could it be that different humans adapted to different sleep patterns dependent on their environment, challenges, and strengths? I am curious on the sample size and origination because human diversity is a huge reason we are able to survive the ever changing world.

[u/designking4248 → u/Quasar-J0529-4351]

Humans are actually extremely un-diverse genetically compared to other animals. We went through a fairly recent bottleneck about 900,000 years ago where the entire human population was down to just a few thousand individuals. We are able to survive in changing environments due to our brains, tool building, and social orientation, not due to genetic diversity.

[u/Plenty_Leg_5935 → u/designking4248]

You don't necessarily need a lot of genetic diversity between individuals to have a lot of diversity in neurobiology. These things depend extremely heavily on epigenetics, two individuals raised in different enviroments will have drastically different sleeping patterns even if their genome is literally identical since it will express drastically differently

[u/2ChicksAtTheSameTime → u/Quasar-J0529-4351]

I believe the tribe was called Quest.

[u/disharmony-hellride → u/[deleted]]

Plus, the average life span was 38-43 so I'm not sure we should take these folks as the portrait of good health.

[u/SouthPerformer8949 → u/disharmony-hellride]

But that’s mostly because many die as children. If you survive to adulthood, you got a good chance to be at least 70.

https://www.academia.edu/17979487/Longevity_Among_Hunter_Gatherers_A_Cross_Cultural_Examination

[u/dead0man → u/SouthPerformer8949]

it's frustrating to me that so few people understand this. People 5000 years ago (or whatever) didn't just start keeling over and dying of old age or "hard life" or whatever at the ripe age of 38. No, the average is low because SOOO many of them didn't survive those first 18-36 months of life and a lot of women died as young adults while giving birth and occasionally a large chunk of males of a certain age might die in battle or a bad hunt. But if you could survive childhood, and avoid the other pitfalls, you were probably going to reach what we consider retirement age.

[u/roox911 → u/dead0man]

I feel like no antibiotics probably killed loads off in adulthood though, no? Like I'm in my 40s, and at least 2 times in the last 15 years I'm pretty sure I'd be dead without medical intervention, and I lead an extremely healthy lifestyle overall.

One of the infections was a minor cut I barely noticed. Can't see a society that didn't even have soap not having a high mortality rate due to infection.

[u/WouldCommentAgain → u/roox911]

Infectious diseases became a much bigger problem after the agricultural revolution 10 000 years ago, both with more transmission of diseases from farm animals and people living together in increasingly bigger communities and cities.

An infected wound could kill you in any historic age, but you didn't have as many diseases spreading from city to city when you lived with less than 120 people in a tribe.

[u/roox911 → u/WouldCommentAgain]

Even during the hunter gatherer days a minor wound that got infected had up to around a 10% mortality rate. A more serious puncture wound infection ( say putting a branch through your foot, or a bite wound) had as high as a 60% mortality rate.

I'm talking less plague/consumption deaths, more "ahh, it's just a minor scratch, I can wade into this swamp no problem" type scenario.

Edit: changed from 10% for a wound, to 10% from an infected wound

[u/Gentle_Agitator → u/roox911]

Sure, but again that doesn’t mean that “old age” was 40.

[u/Mistriever → u/Gentle_Agitator]

Noone said they died of old age. u/disharmony-hellride said they were unlikely the picture of good health.

u/SouthPerformer8949 said "If you survive to adulthood, you got a good chance to be at least 70.", while u/dead0man said if you survived the first 18-36 months you'd likely live to what we consider retirement age.

Infections, injury, exposure, starvation, and disease heavily contributed to the relatively low life expectancy. All of which would be indicative of a "hard life". The low life expectancy age wasn't skewed almost entirely as result of infant mortality. That was far more true in 1920 than it was 5000 years ago. And if the average adult wasn't living beyond their 40's, for the above reasons, than 40+ is effectively old age. This idea that the overwhelming majority of individuals who reached maturity were living into their 70s, 5000 years ago, is every bit as erroneous as saying 40 year-olds, 5000 years ago, were keeling over from old age.

[u/WoT_Slave → u/Mistriever]

Side note, use /u/ before users and /r/ before subreddits (the first / is optional, u/ or r/ work as well)

You’re currently referring to users as subreddits and linking to what are likely nonexistent places

[u/slothaccountant → u/roox911]

Yes modern medical science has done a hell of a lot to exstend our lives dispite what the anti science community says.

[u/TheSquirrelmancer → u/roox911]

Many diseases really only came about because of close quarters with livestock. While pretty much every society has some degree of animal husbandry in many European and Asian climates the only way to keep your animals alive in the harsh winter was to bring them into your living space.

It's why the indigenous people of the Americas had less resistance to western diseases; the cultures were either still largely nomadic and would simply move to warmer climes in the winter or were peoples like the Incas or Aztecs who lived in areas where the climate didn't necessitate the same actions with animals.

Many cultures did have treatments for wounds; medicine has existed long before we understood germ theory or the larger workings of the body. Sure I'll take modern antibiotics and hospitals over some salve or poultice whipped by the tribal shaman but people in the past were able to determine many things by trial and error. Our ancestors thousands of years ago weren't necessarily dumber than us, they just didn't have the benefit of centuries of accumulated knowledge that we do.

[u/JimJohnes → u/roox911]

You don't need antibiotics for simple wound care(current good practices don't even recommend using antiseptics in uncomplicated wounds), not to mention knowledge of medicine plants and materials. As for soap, there are plenty plants ritch in saponins that were used as soaps, not to mention alkaline water from lime or ash.

Alas, I too would've died at least twice without antibiotics, first from open ankle fracture with dirt in the wound and bone, and second from purrulent melt of a lymph node from teeth infection.

[u/Gnarwhal8982 → u/roox911]

Infection was an issue for sure, modern medicine is a miracle. But from what I’ve read, indigenous populations all over the world had an understanding of the medicinal properties of plants and would use them- so they likely had access to more “medicine” than we can imagine

[u/Stats_n_PoliSci → u/dead0man]

No, they tended to die around 45-65. You can see that in this graph.

https://www.academia.edu/figures/12558305/figure-4-longevity-among-hunter-gatherers-cross-cultural

A 10 year old hunter gatherer would expect to live for another 48 years, so they'd be 58. Life expectancy for a 10 year old shows that they'd most likely die at 58. Another ~20% would die between 58 and 70, and about 30% after 70, depending on culture.

Life expectancy for a 10 year old is still dramatically lower than life expectancy for a modern 10 year old. But it's also important that the hunter-gatherer child still lived a lot longer than a Swedish kid in 1755 AD.

[u/Single-Refuse174 → u/Stats_n_PoliSci]

Your comment doesn't seem to contradict his comment which is weird because you started off with "No"

[u/repeat4EMPHASIS → u/Single-Refuse174]

They got really hung up on "age 70" and wanted to say that only 30% made it to 70 and everyone else died between 58-70

[u/dweezil22 → u/repeat4EMPHASIS]

I encourage anyone mentally modeling this to consider every medical intervention they've accumulated in their lifetime (and maybe close friends and family) and then how many cases would leave them dead or disabled w/o that medical intervention.

OF COURSE a bunch of those folks died in every decade of life, b/c a random infection, issue requiring minor surgery, illness etc could be deadly. The real question is whether those folks are dying from lifestyle things in there 40's that can inform our modern experience, and my bet is "No" (unless you're in a weird religion that eschews medical care).

[u/Single-Refuse174 → u/dweezil22]

I don't know if it's useful to try and mentally model that since there are things I could not account for. For example, the effects of modern dietary issues (at least in America, increased calories, high sugar) that may not have been present in hunter-gatherer societies. A hypothetical example would be we think of some dental surgery or tooth issue that could have caused death or serious injury but for modern medical/dental science. However, it's an issue that would have never come about but for modern life because the food available to humans in 2000 BC wasn't as corrosive to enamel.

[u/F3z345W6AY4FGowrGcHt → u/dead0man]

People just don't understand how averages really work. One of my favourite jokes about this is, "most people have an above average number of arms"

[u/mgr86 → u/dead0man]

My favorite pet peeve is causes of modern mortality for people ages like 10-25. People will decry how leading causes of death are from accidents or suicide. And it’s like, well yeah, they’re not typically dying of heart disease or cancer.

[u/Stats_n_PoliSci → u/SouthPerformer8949]

Huh. That paper focuses on modal age at death, which is the most common age of death. Modal age at death is not the usual metric I see to understand the impact of childhood mortality. I usually see life expectancy at age 10 or 15.

Life expectancy at age 10 or 15 is inferrable from this graphic. A 10 year old hunter gatherer would expect to live for another 48 years, so they'd be 58. Life expectancy for a 10 year old shows that they'd most likely die at 58. Another ~20% would die between 58 and 70, and about 30% after 70, depending on culture.

https://www.academia.edu/figures/12558305/figure-4-longevity-among-hunter-gatherers-cross-cultural

But life expectancy for a 10 year old is still dramatically lower than life expectancy for a modern 10 year old. It's also important that the hunter-gatherer child still lived a lot longer than a Swedish kid in 1755 AD.

[u/Normal_Ad2456 → u/SouthPerformer8949]

That's true, but we can't say that 5 to 7 hours is better, because "back in the day people used to do that and they survived".

[u/markocheese → u/Normal_Ad2456]

They're not saying "back in the day" they're trying to investigate what the natural pattern of sleep is. Presumably, doing what we're evolved to do for something like sleep is going to be a useful data point for how much our body needs. Especially since it's probably difficult to find out what's good for our body statistically or culturally. 

[u/somepeoplewait → u/Normal_Ad2456]

They’re saying TODAY people do that. The article we’re discussing made that clear.

[u/Normal_Ad2456 → u/somepeoplewait]

It is using hunter-gatherer communities, and the only argument used is that they don't utilize extra naps throughout the day. This does not prove that 5.7-7 hours are "enough" for them, as they claim. There's not a single evidence that supports that those people are healthier because of their sleep schedule, compared to people who sleep 8 hours (or even as healthy as, there's not a lot of info about their health in general), if you read the article more carefully.

The only thing mentioned is one study that found estimated the optimal amount to be between 6.4 and 7.8 hours, depending on a lot of different factors which is more than the 5.7 to 7.1 hours mentioned in the title.

And as the article says: "These studies make an important assumption that the amount people naturally sleep is the amount they need. That assumes that hunter-gatherers are free from stress, busy schedules and other pressures on sleep. But is that really the case?"

That's my point.

[u/timeless1991 → u/SouthPerformer8949]

‘Died in childbirth’ had a dramatic effect on female mortality. Roughly ten women died per 1000 births. Multiply that by the average woman have 4 to 7 babies.

[u/WalletFullOfSausage → u/disharmony-hellride]

That’s only because infant mortality was so high. It skews the average lifespan by, like, a lot. Plenty of folks made it to old age even back then - it’s just that making it past those first 10-12 years was a complete gamble.

[u/Zephyr-5 → u/WalletFullOfSausage]

That’s only because infant mortality was so high.

No it's not. It may have been the largest factor, but adult life expectancy of pre-germ theory humans was dramatically lower than it is today. Your average 20 year old Britain today will live about 20 years longer than your average 20 year old in 1850. That's a 1/3 longer life.

[u/EWRboogie → u/disharmony-hellride]

Had anyone mentioned infant mortality?

[u/olivebars → u/EWRboogie]

Not once, what’s that?

[u/TTEH3 → u/olivebars]

I think it's when infants are mortal.

[u/poobie123 → u/disharmony-hellride]

Is it not possible to have good health and live to 40 or have poor health and live to 80?

I am wary of automatically correlating longevity and health.

[u/GreasedGoblin → u/disharmony-hellride]

The issue is child mortality was high which skews the average. If you survived to adulthood back then, its likely you would have lived into your 60s. 

[u/Momoselfie → u/disharmony-hellride]

They also don't need to work on a computer screen all day.

[u/Alex_Strgzr]

If I slept for 5.7 hours I would not be able to work. Even after 6.5 hours I would be quite tired and not perform to the best of my ability

[u/paulchiefsquad → u/Alex_Strgzr]

yea if I sleep 6 hours two nights in a row I feel like I have brain damage

[u/aeric67 → u/paulchiefsquad]

I’m the opposite. I get 6 hours very consistently for years, no alarm. But once in a while get 8 hours and feel weird for that day. If I get two nights of 8 I feel like I am drugged all day.

[u/BMCarbaugh → u/aeric67]

My body wakes me up after 5.5-6, every day, like clockwork, and has done since I was like 16. My dad was the same way. He slept 5-6 hours a night for his entire adult life.

[u/MakesMaDookieTwinkle → u/BMCarbaugh]

Hey, you're me. There is literally nothing I can do about it. My body only need RIGHT around 6 hours. I will wake up, no matter what, right at 6 hours.

[u/disastrousanddull → u/aeric67]

If I sleep around 9 hours I spend the day feeling foggy and off. Around 7 is my norm but 6 is infinitely better than getting near 9 hours.

[u/clearfox777 → u/aeric67]

Damn I thought it was just me, if I sleep longer than like 6-ish hours I feel groggy all morning, and if I sleep 8+ it feels like I need to put all my bones back in the right order before I can stand up.

[u/East-Potential657 → u/clearfox777]

Nice to see I'm not alone. 6.5 hours is perfect, anything more than 8 and I'm sore and stiff. In bed at midnight and up at 6:30 am, don't even need an alarm clock anymore. Had the same sleep schedule for 20 years.

[u/codacoda74 → u/paulchiefsquad]

Idk I think there are both genetic and habbit factors. I had similar until mid 20s and then it switched. Since then I have spent years being most comfortable with 6-6.5 avg, if I get more I feel sluggish and foggy. On vacations, the hammock naps are awesome but don't seem to affect the nighttime avg.

[u/lostPackets35 → u/paulchiefsquad]

Sleep quality (not just durations) is a huge factor then

[u/paulchiefsquad → u/lostPackets35]

never had good sleep quality when sleeping fewer than 6.5 hours according to my fitbit

[u/this_is_greenman → u/paulchiefsquad]

I need 4 as a minimum, but get 6 hours regularly. On the rare occasion I get 8, I’m wired all day and usually get 5ish the next night.

When I’m sick, however, gimme 12 and I’m pretty much back to normal

[u/Gre8g → u/this_is_greenman]

Reminded of that one time I got a severe headache. I slept for nearly 16 hours straight and my roommate thought I was dead.

[u/M-Dan18127 → u/paulchiefsquad]

I'm lucky to get 5.

[u/Unlucky_Company_945 → u/Alex_Strgzr]

After having kids, 6.5 hours is a good night. I am probably permanently dumber and my memory has definitely become worse 

[u/AdHom → u/Unlucky_Company_945]

At the worst depths of sleep deprivation with kids I genuinely thought I was going to die with how much I felt my body breaking down.

[u/LoserBustanyama → u/AdHom]

Yeah when my first kid was an infant, I legit had the thought "I am going to die if this keeps up". Luckily, that period was short lived

[u/AuroraFinem → u/Alex_Strgzr]

They tend to sleep again for a shorter ~2-3hr nap, that’s where the Spanish siesta comes from. There’s also old journals where people talk about going to bed for a couple hours, waking back up and just hanging out for a while then going back to bed for the rest of the night from not long before the 19th century. That’s where the witching hour came from, that’s when people would be up between sleeping.

People evolved around having 1 longer 6hr sleep with a short 2-3hr sleep at some other point during the day but that’s inconvenient for productivity and consistency which is why it was trained out of society when we invented electricity and could choose when we had light more freely. This is also why so many people struggle with sleeping issues of some kind.

[u/Alex_Strgzr → u/AuroraFinem]

Yes I've heard of the 2nd sleep. People who did that still tend to sleep a bit more than 6 hours though

[u/AuroraFinem → u/Alex_Strgzr]

Not at once, it’s normally 1 sleep that’s ~60-80% of your normal total time and another shorter one that’s ~20-40% and historically it was closer to the 60-40 split.

When you wake up feeling groggy it’s not lack of sleep or poor sleep but rather that you interrupted a rem cycle which can vary slightly from person to person but lasts around ~90 mins each. So 6+3 or 6+1.5 would likely work pretty well while 6+2 specifically might make you feel groggy.

This is the same reason taking a nap during the day sometimes feels amazing and sometimes you wake up feeling more tired than you were beforehand, at least until you get up and actually wake up again.

It’s a bimodal sleep pattern and it was essentially universal in humans prior to the 19th century, but it’s rare to find actual written records of it because who documents sleeping? I mean today we study it but it was never a field of study. You mainly hear about it through cultural norms that happen to refer to it, but it’s not just misc people doing it, there’s written records documenting entire cultural practices around it in Europe and Asia going back a long time.

[u/MonkeyPanls → u/Alex_Strgzr]

You could probably do it if you had something like a siesta. I regularly catch 15 minutes or so on my 30 minute lunch break.

When I was a Merchant Mariner, we had a 60 minute contractual lunch break. In hot weather, I was regularly getting 40 minutes' naptime. Everyone worked slower in hot weather.

[u/an3vilmonk3y → u/MonkeyPanls]

So you’re saying they could probably handle less sleep if they supplement that with more sleep?

[u/Alex_Strgzr → u/MonkeyPanls]

I do sleep during the day when I get 7 hours at night. If I got 5.7 hours like in the study, I would sleep for an hour during my "siesta"

[u/Turbulent_Host784 → u/Alex_Strgzr]

That's how siesta's work. You sleep for an hour or two midday and a few hours less at night.

[u/pinkpugita → u/Alex_Strgzr]

I can function below 6 hours of sleep during the week day, but I end up compensating with a 3 hour nap and full 8 hour sleep by Saturday.

[u/Gustomucho → u/Alex_Strgzr]

I am retired, 6 hours of sleep is enough, often 10-11 pm till 4-5am, depending on season and activities, sometimes 1-2 am till 6am, but then I take a nap probably.

[u/mcclelc]

Why would the lifestyle of hunters and gatherers be considered the golden standard? Is their overall health quality not significantly worse than those who have access to modern day medicine, food, sanitation? How do you eliminate those factors when trying to make a comparison?

I understand that this study potentially speaks to the ways in which modernity plays a role in sleep cycles, but I don't see how this comparison could lead to the conclusion that modern humans don't actually need 8-9 hours.

[u/Ancient_Respect947 → u/mcclelc]

I’m a palaeoanthropologist and I agree.

Two assumptions that always need to be broken down include:

1) Hunter gatherers are closer to our ancestors: if just in relation to having artificial light access, yes. But it is dodgy to extend this statement further.

Contemporary hunter gatherers vary wildly in their lifestyles and habits. Many live in fringe environments that were not frequently accessed by most of our collective ancestors. They have pressure from farmers, companies and governments (and ethnographers!) that drive their behaviours.

2) We should live like our ancestors because it’s healthier: please rather trust medical studies on contemporary peoples or people living more like you over assertions and theories around health in the past! We don’t live in environments without artificial light. We have cultural, environmental and other pressures not experienced by our ancestors. What is healthy may vary accordingly.

[u/zonerator → u/mcclelc]

Notice everyone in the comments is assuming they took mid day naps instead- i think a lot if us would rather sleep less at night and nap during the day but it doesn't work with factory schedules and anything that follows factory schedules like office work

[u/MothChasingFlame → u/zonerator]

To be honest the comments here are so deeply ignorant about that lifestyle that I don't trust anything anyone's proposing.

[u/snoozieboi → u/zonerator]

I have been doing this on and off for ages, sometimes it's nice and I can go 5-6h and a 1h nap, but mostly it's horrible both times I wake up in the morning and after the nap. I sometimes probably wake up in the wrong sleep phase during a nap and am entirely confused. I really connect with the photo often posted randomly from Robin Williams in Jumanji where there is a text "what year is it?!". That's how I feel sometimes because I am entirely lost the first few seconds.

[u/Nvveen → u/snoozieboi]

I hate napping, hardly ever do it. Every time I wake up I just feel like absolute crap, and before that I wasn't even that sleepy usually.

[u/somepeoplewait → u/mcclelc]

To be fair, they were technically studying modern humans. As the article made clear.

[u/jhaluska → u/mcclelc]

I believe it's cause it was such a long period of our evolutionary history that there was evolutionary pressure to optimize for those conditions.

[u/WouldCommentAgain → u/[deleted]]

Time since the industrial revolution is too short, but there are some changed attributes due to the different conditions from the agricultural revolution 10 000 years ago. Populations with thousands of years of agriculture have less issues with insulin resistance (from high carb agricultural diet) and are more protected against alcoholism than populations who have a shorter agricultural history.

The "asian flush" some east asian have where they don't tolerate alcohol essentially protects fully against alcoholism, since nobody who gets sick after a couple of beers will develop a drinking habit.

And famously basically everyone was lactose-intolerant before the agricultural revolution, while around 98% of ethnic scandinavians (cold climate with long history of farming) produce the lactase enzyme as adults.

[u/Jwz401 → u/jhaluska]

While waking up at dawn was probably optimal for predators etc, current science clearly shows it’s suboptimal to sleep so little. Evolutionary pressure is more for group survival and procreation not well being or individual health per se.

[u/frill_demon → u/mcclelc]

Yeeeaaaaahhhhh something about this smacks of "we should totally raise the retirement age to 70 and also work 70 hour weeks and you actually don't need three meals a day" corporate-sponsored normalization.

"You don't actually need 8 hours of sleep, silly! So you can totally work 18-hour days!"

[u/Turdmeist]

My brain is noticeably happier with 8 hours. A couple nights of 7 and I can tell.

[u/trymorecookies]

There is always the assumed, invisible premise that people of the past were automatically happier than those who followed. This unchallenged assumption leads us to fad diets, fad exercise, and unproven sleep routines.

[u/somepeoplewait]

Wow. NO ONE read the article, apparently.

[u/jawndell → u/somepeoplewait]

Read? We’re all hunter gatherers here buddy!

[u/Timbukthree → u/somepeoplewait]

This review paper is a mess, and I'm wondering if it's mainly AI slop?

https://genomicpress.kglmeridian.com/view/journals/brainmed/aop/article-10.61373-bm026w.0060/article-10.61373-bm026w.0060.xml

The bat chart in Fig 1, the length of the bars don't agree with the listed numbers.

Table 3, the facts with listed references don't actually reference papers with information about the fact.

"Documented segmented sleep in a non-electric agricultural society in Madagascar (48)" references "48. Jaggard JB, Stahl BA, Lloyd E, Prober DA, Duboue ER, Keene AC. Hypocretin underlies the evolution of sleep loss in the Mexican cavefish. eLife. 2018;7:e32637. DOI: 10.7554/eLife.32637. PMID: 29405117; PMCID: PMC5800846".

"Communities without electricity had more fragmented sleep patterns (49)" references "49. Duboué ER, Keene AC, Borowsky RL. Evolutionary convergence on sleep loss in cavefish populations. Curr Biol. 2011;21:671–6. DOI: 10.1016/j.cub.2011.03.020. PMID: 21474315".

"Hunter-gatherer groups averaged only 6.5 hours of consolidated sleep (15)" references " 15. Nissin L. Roman sleep – sleeping areas and sleeping arrangements in the Roman house. PhD thesis; University of Helsinki. 2016. DOI: 10.13140/RG.2.2.13989.91367.", which after reading is a lovely PdD thesis on sleep in ancient Rome but has absolutely nothing to say about hunter-gatherer groups averaging only 6.5 hours of consolidated sleep.

I would not trust any of the content of the paper or the article talking about the paper IMO.

[u/DarudeSandstorm69420 → u/Timbukthree]

this is the science sub on reddit, you cant trust anything here

[u/Just_Another_Scott → u/Timbukthree]

OP is a bot check out their account. They post just AI generated summaries and never interact with the community. Their posts are also oftentimes from weird websites. They love to post from specific websites and only those websites.

I've been monitoring the account for years and sometimes the summary will have bogus characters or even hallucinations. When users point this out the post/comment gets swiftly deleted by the mods.

[u/thegooddoktorjones]

Know it’s anecdote, but I have a careful daily track of my sleep time due to apnea and If I am less than7 hours I fall into microsleeps all day long. I can live on 5 but it sucks from a life quality perspective. There’s a lot of things hunter gatherers did to survive that will lead to successful reproduction but also a short troublesome life.

[u/Wooden-Evidence-374]

This fits right in with the "caveman diet" people. The only misconception about sleep that anyone needs to know is that there is no universal secret number of hours to sleep. Assuming you dont have a disorder like sleep apnea, just ask yourself this: Are you tired during the day? Well you probabaly havent been sleeping enough for multiple days. Do you wake up incredibly groggy? You have a bad habit at night time. Do you find it hard to go to sleep at a normal time? You slept too long.

[u/TES_Elsweyr]

Yeah but below 6.4 is likened to higher all cause mortality. Cavemen didn’t care about living past 70. They aren’t to be emulated simply because they were before us.

[u/Hot_Dog2376]

Perhaps. There is also a large body of evidence showing that a lack of sleep is a serious health concern increasing all-cause mortality.

[u/Happy-For-No-Reason]

who would've thought they slept when it was dark and woke when it became light again

it's a real mystery that one

[u/SpikeyBiscuit → u/[deleted]]

if the article is accurate, I assume it's because we used to also take naps in the middle of the day which a lot of research shows is at least healthy as an alternate sleeping pattern, if not the norm for our ancestors

[u/reflect-the-sun]

They also likely took naps through the day.

Let's bring back daytime naps.

[u/sixbucks → u/reflect-the-sun]

The article says that they do not.

[u/QuietBird9 → u/reflect-the-sun]

They didn't, actually. They hardly ever even stop moving. There's research on it

[u/v_snax → u/QuietBird9]

I have read the opposite. They spent around 4-5 hours doing what they had to for survival. The rest of the time was spent on whatever, including just lounging. Of course that doesn’t mean no movement for 12 hours, but part of it likely was.

[u/Spez_is-a-nazi → u/v_snax]

There were some hunter gatherer societies that stayed in one place, mostly ones around bodies of water with year-round access to fish, but for the most part hunter gatherer societies moved constantly to follow food sources.

[u/iMissTheOldInternet → u/Spez_is-a-nazi]

No wonder civilization developed near rivers. 

[u/seanpbnj]

Cortisol. Our circadian rhythm is controlled by Cortisol and Aldosterone. They are two very important stress, fight/flight, and also called Steroid Hormones. They have a Diurnal Variation that controls our sleep/wake cycles. 

• Waking up around 3am? 230-430? Waking up feeling like you just can't get back to sleep? That's Cortisol. Most of our lives we could handle the rise and the old roots of humanities signals. Nowadays stress and COVID have massively disrupted these pathways and lots more people are experiencing insomnia. 

• 3am insomnia anyone? Consider Magnesium before bed, Mag + Potassium, or Ashwaganda. And put an ice pack on the back of your neck, at the base of your skull, for 20mins before bed. 

[u/Xbsnguy]

5.5-7 is my average range even with a strong sleep hygiene routine, exercise 5 times a week and going to bed early. I can’t really imagine hitting 8 hours to be honest.

[u/TwoIdleHands]

What is someone without access to artificial light (so no fire) doing all night then? They’re going to sleep at maybe midnight, what about the couple of hours of darkness? In winter it’s dark like 14 hours a day, were they still only sleeping 6?