We used to sleep twice each night

http://www.delanceyplace.com/view_archives.php?2137

by anigbrowl • 13 years ago

417 107 13 years ago

zachlatta2• 13 years ago

This makes me wonder what the optimum sleeping schedule actually is. Is it sleeping twice each night, like mentioned in the article? Or is something like the uber schedule better? I've been on the "hacker" schedule for the past month or so (10PM to 2AM) and I've been getting more work done than ever.

derengel• 13 years ago

At what time do you wake up? do you sleep during the day? do you take your coffee at 10PM ?

zachlatta2• 13 years ago

Wake up around 2AM, no sleep during day. Don't drink coffee regularly.

gajomi• 13 years ago

I'm sure it depends on your optimality criterion. I have looked into the research behind this two-sleep phenomena, and it seems like a highly plausible theory for human before before the last couple hundred years. One might expect this to be close to some kind of evolutionary optimum characteristic of the last 3000 or so years that most of humanity has lived in cities. This environment, I think, should be quite different from our society where we have things like "hackers" and are responding to interesting comments from the internet at one in the morning (maybe I should go to bed).

grannyg00se2• 13 years ago

I suggest (with no proof or expertise) that the optimum sleeping schedule is to sleep when you are tired and wake when you are no longer tired. This is very difficult to achieve given life's typical demands.

I've recently applied this same philosophy to eating. I eat when I'm hungry and I stop eating when I am no longer hungry (not when I'm "full").

WalterSear4• 13 years ago

Except we have evidence that you can sleep too much.

pjscott• 13 years ago

Artificial lighting changes the time when you become tired.

sliverstorm2• 13 years ago

IMO it depends a lot on what you want to achieve. "Optimum" is dependent on your metric. In other words, spreading your sleep out through the day could easily be optimum for activities that respond well to division. You get to re-approach your tasks refreshed, several times a day. On the other hand, if you are a farmer, daylight is precious and you can't do much at night aside from prepare for the next day.

The most important takeaway- as always, "optimum" only has meaning in the context of what exactly you hope to optimize for.

goodcanadian• 13 years ago

> . . . if you are a farmer, daylight is precious and you can't do much at night aside from prepare for the next day.

A nitpick, but I don't think this has been true for many decades. There are lights on tractors, you know. True, daylight is a better time for many farming activities, but during harvest, my father will sometimes work from 6am-2am if the conditions are good. (Yes, 20 hours though a nap after lunch is possible if there is someone else around to run the combine during that time).

cfeduke• 13 years ago

It seems like this phenomenon is something you'd expect to hear about from thru hikers on the Appalachian Trail.

Never specifically asked or looked for it, but never heard anything about it either.

Ogre• 13 years ago

I hiked 800 miles on the AT two years ago. I can vouch for it. I didn't think much of it at the time, but I've heard about this since and it fits. I frequently woke up sometime in the middle of the night. Sometimes I'd read for a bit and sometimes I'd just lie there and listen.

I just chalked it up to more hours in bed and being really REALLY tired when going to bed, but it makes total sense that the lack of artificial light played a big part.

rayiner• 13 years ago

I wonder how much of this is because babies wake you up in the middle of the night and this was before birth control so most people had a baby at home at any given time.

1123581321• 13 years ago

Babies in such societies sleep with the mother. They don't wake much because they sleep more than adults, and if they wake they're easily nursed so remain calm. It's the modern Western practice of separating babies from parents at night, and sometimes not nursing, that results in what you describe. Additionally, colick, the name we give to some infant's tendency to cry excessively, is often related to disagreeable food eaten by the mother, something more likely to happen in a sophisticated society that eats a wider variety of food.

Also, if babies naturally are biphasic sleepers (not saying they are not, just that they're not naturally as disruptive as modern practices make them), that supports humans being naturally biphasic but suppressing it through habits and environments.

dougk16• 13 years ago

More evidence perhaps: http://en.wikipedia.org/wiki/Midnight_Office

cefarix• 13 years ago

Interesting. Islamic tradition also has a "night prayer": http://en.wikipedia.org/wiki/Tahajjud

furyofantares2• 13 years ago

There are lots of people in the world today that aren't exposed to artificial light daily -- I wouldn't expect such a difference in sleeping habits to go unnoticed.

catshirt• 13 years ago

so says the article.

furyofantares2• 13 years ago

Thanks, I thought I'd read the entire article but I believe I missed the last two paragraphs.

wildgift• 13 years ago

Ideology is a powerful thing. The ideology of industry and work in modern society keeps us blind to many things.

hkmurakami• 13 years ago

Ooh I just got a 404 (ish) page that at first glance looked like an attack page warning.

Might want to change this.

http://i.imgur.com/77XpT2l.png

anigbrowl5• 13 years ago

HN strikes again! Cahced:

http://webcache.googleusercontent.com/search?q=cache:IAiep0K...

zissou• 13 years ago

Like the wise scholar in England wrote, I'm most productive after a nap but before I go to bed.

Is taking a nap then "going to bed" later basically the same thing as a 2 sleep night?

I think naps are a good modern example of a 2 sleep night. I wonder when people began napping? The Google Ngram Viewer makes me think we've been napping for years [1], except perhaps right after WW2, but then 1970 happened and we started getting tired. :)

[1] http://books.google.com/ngrams/graph?content=nap&year_st...

greetings• 13 years ago

Interestingly the british english corpus has a fairly even reference to napping. Though there is a slight downward trend to the graph.

I have also included napping and siesta in the plot. These have a fairly constant use.

http://books.google.com/ngrams/graph?content=nap%2Cnapping%2...

philwelch2• 13 years ago

Churchill himself, during WWII, was insistent upon his midday nap:

"You must sleep some time between lunch and dinner, and no half-way measures. Take off your clothes and get into bed. That's what I always do. Don't think you will be doing less work because you sleep during the day. That's a foolish notion held by people who have no imagination. You will be able to accomplish more. You get two days in one-well, at least one and a half, I'm sure. When the war started, I had to sleep during the day because that was the only way I could cope with my responsibilities."

mgkimsal2• 13 years ago

It's an interesting mindset, and I wonder if he'd ever given thought to letting the troops take afternoon naps. I can't imagine that they did, but wonder if it would have been beneficial or not.

bart42_0• 13 years ago

Many people are having a siesta in the afternoon, wich is basically the same as having a nap, isn't it?

davidroberts• 13 years ago

I found myself drifting into this pattern about a year ago, when I had moved into a new town by myself without much to distract me. I found myself getting sleepy about 8 pm, going to sleep, then waking up around midnight for and hour or so, then going back to sleep and waking up (naturally, without an alarm clock), about 4:30 am to get ready to leave for work at 6 am.

I found the late night period very relaxing, and productive if I decided to read or write something. I found an article similar to this one around that time, and thought "Aha! That explains it!"

Unfortunately, my family has come to join me here, and I've made a lot of new friends, and I'm definitely not going to sleep at 8 pm anymore. So the phenomena has ended. I kind of miss it!

aton• 13 years ago

Why should this be a mystery? It was a few centuries centuries ago, not thousands of years ago. Shouldn't such widespread habit be well documented?

agrona• 13 years ago

This reminds me of how the British Navy forgot the cure to scurvy after 150 years. http://idlewords.com/2010/03/scott_and_scurvy.htm

noinsight• 13 years ago

It's interesting how sometimes an article seems ridiculous at first but quickly becomes extremely interesting... This was one of those.

ldng2• 13 years ago

Like when Romans invented the scalpel forgotten only to be reinvented in the 19th century (stretching a bit since IIRC the Arab kept using it) ?

That a subject that never cease to amaze me. Civilizations rises and fall and with them knowledge. To me, Dan Simmons kind of use that in Ilium and Olympos as background. What will happen when our digital civilisation falls ?

JoeAltmaier• 13 years ago

We can never 'fall' again as thoroughly as we did in the past. Too many artifacts; too many documents/cds/books/computers containing the technology to restart a civilization.

claudius• 13 years ago

‘Documentation’ was not always as cheap as it is today. If it takes hours to engrave a few words in a stone board or if a single page of paper is worth more than a simple meal, you think twice about what you ‘document’. Chances are that such common practices were considered that obvious that they didn’t need documentation on their own, similarly how you would likely not include ‘plug the computer into a power supply’ when asked to tell a relative how to set up theirs.

snowwrestler• 13 years ago

Why document something that everyone does? History is captured in sources like published news, government statistics, personal letters, etc. A personal behavior that is widely understood would not necessarily be newsworthy enough to capture in any of those places.

This is a real problem for historians: unusual occurrences are usually well-documented in permanent media; everyday life usually is not.

Elv13• 13 years ago

I do this all the time. I work/go to school, come back exhausted, eat, sleep until midnight, wake up, code/do homework around midnight, then go to bed again. I am not the only one doing this even in modern society. Most of my personal projects commit log is during that time. Of course some people think there is something wrong with me, but I don't think so.

more_original• 13 years ago

Something similar happens to me. When I'm really exhausted from the day, I fall asleep while reading or relaxing (maybe from 9pm to 2am) and then wake up again. I'm then awake and do a few things for an hour or two. I like how it messes with people when you send them emails at 4am. Then I'm getting sleepy again and sleep the rest of the night normally.

mbenjaminsmith• 13 years ago

Wow, my wife has started to do this and I thought it was really strange. I'm happy to see it's not unheard of. We live "normal" lives of course, careers and lightbulbs, but she will often go to bed early (by my standards) and wake up sometime after midnight and work for an hour or two before going back to bed.

badgar• 13 years ago

Whenever I go to bed early, I wake up for the best hour or two of my life around midnight. Good to know I'm in working order.

homeomorphic2• 13 years ago

That often happens to me also, except I feel absolutely shit while awake. I'm very awake, and not tired, but my mind races so uncontrollably it's almost painful. My brain also decides to consider every problem in life from the worst possible perspective.

anigbrowl5• 13 years ago

I don't want to make armchair diagnoses, but based on my own experiences it's worth seeing someone about that if it's happening frequently.

DocG• 13 years ago

Same here. I get tired early but I force myself to stay up, because I will wake up around 12 then.

Another interesting pattern is that I can't go to sleep after midnight. I have to be really tired to start sleeping between 00 and 01. 21-00 is all good, also after 1 or 2 I can start sleeping easily

Well, I think I will give my new sleeping pattern a chance

kanamekun• 13 years ago

The BBC wrote a great piece on Thomas Wehr and Roger Ekirch last year... they also added some nice color commentary on artificial lighting in the 17th century and beyond:

The myth of the eight-hour sleep

http://www.bbc.co.uk/news/magazine-16964783

mimiflynn• 13 years ago

I had previously forwarded this BBC article to some of my friends, many of whom replied with "this is just like me!"

I'll wake up for a couple of hours every now and again and just read and walk around the house and do things. In the morning, I always feel rested.

chromaton• 13 years ago

I'm up after sleeping a few hours tonight and it feels great.

philmcc• 13 years ago

It'd be great if there were a number of "Huh? Doesn't everyone do this?" comments at 12am PST.

(east coasters were already in their second sleep by the time it was posted)

mattm• 13 years ago

Since getting married, I noticed that my wife does this. She usually gets tired and drifts off to sleep around 9 after dinner. Then she'll wake up for an hour usually between 12-2 and do some things before going back to sleep.

chubot3• 13 years ago

Hm this is interesting. I have been alarm clock-free for many years now.

Lately I find that my sleep is segmented; I was wondering if it's a bad thing. I generally sleep from 3am to 8am or so, and then I wake up, eat an apple, and read the Internet. And then I sleep from 9am to 11am again. It's been pretty consistent for awhile. It seems to be the pattern of 2 REM cycles and then 1, since I believe people generally get 3 in a night.

It's perhaps not the same thing, since it seems unrelated to daylight. It may be related to information retention. I generally wake up and write some notes about what I thought about during my sleep (lately I find that my dreams are almost like thinking). And then I do some googling related to those topics. And then I go back to sleep and retain it.

Another thing that's interesting about sleep is that humans have a dimorphism between early birds and night owls. I read a hypothesis that it's because it maintains the property that some members of a group are a awake at all times, e.g. to guard against predators and so forth.

matiasb• 13 years ago

where did you read about that hypothesis? sounds interesting

chubot3• 13 years ago

I thought I had read it on Hacker News like a year ago or something. But I just spent 5 minutes Googling, and I can't find it now! argh. Keywords were variations of "early late risers dimorphism predators". I will look a little more later.

WA• 13 years ago

I wonder if this hypothesis is true. I wouldn't call myself an early bird. However, when I was on Hawaii for vacation, I slept in a tent and I was tired around 8pm, because it got dark at 6pm and I didn't have more than a small flash light. You can't do much without light and it starts to feel like "late night" if you're in the dark for a couple hours already, even though it was only 8pm.

Back at home, I go to sleep around 12 or 1am.

pmjordan• 13 years ago

Yeah, I've noticed the same in Southern Africa. By 8-9pm I was always totally ready to go to sleep, and I'd actually be pretty happy to get up at 4:30~5:00am. Although we had artificial lighting, it was fairly low-wattage incandescent. During the day, the sunshine was intense (being near-vertical due to borderline-tropical latitude), which probably helped to contrast day & night too.

I should probably live somewhere like that with less reliance on artificial light. I felt so much better being able to just go to sleep and pass out pretty much immediately, and actually felt refreshed and ready to face the day in the morning. That said, I rather appreciate the comforts of highly developed countries…

Aardwolf• 13 years ago

I'm one of those night owls. I'm pretty sure that if I lived millenia ago, I would have enjoyed sitting by the fire with the other night owls, guarding the camp, while the early birds are already fast asleep.

SoftwareMaven• 13 years ago

I do that now, only the fire has been replaced by the warm[1] glow of my laptop and the people next to me are scattered worldwide.

1. Warm thanks to f.lux.

onlehuong• 13 years ago

Gosh darn it! This should had been my thread. I told you (anigbrowl) about reading the "two sleep" and then forwarding you the email. I can't believe it is the number 1 thread.

anigbrowl5• 13 years ago

I love you cupcake :)

mech4bg• 13 years ago

These stories always seem to fit a very nice narrative, using anecdotal evidence to back up what we think sounds right... I would love to see some actual scientific study on this.

I've no doubt that we're not sleeping optimally at the moment with all the artificial light and impositions on our time, but at the same time not everyone sleeps the same way, and just because we sleep differently to how we would naturally do it, doesn't necessarily mean it's worse.

Personally I run best with a good 8-9 hour sleep and a quick 20 minute power nap in the mid afternoon, but other people I know find that more than 6-7 hours sleep exhausts them, or other people who can't stand naps.

I think the best takeaway from this article is that we definitely need better sleep research.

anigbrowl5• 13 years ago

Well, it's a book excerpt (like everything on this site) so chances are there's a lot more in the book's bibliography, or that the concept is developed in greater detail later in the excerpted work.

tripzilch• 13 years ago

Have you ever checked a reference from a book? I don't think hardly anyone ever does, really. Much less than reading an article on the web (when it's just a link to click). I did, once, for an anecdote in Black Swan about statisticians goofing a relatively trivial statistics riddle. Something I found a tad hard to believe, plus the book had been a bit thin on theory[0] so I was itching for some meat. After locating the "cited" paper, it turned out Taleb changed some major "details" to fit his narrative, claiming something entirely different than what the research actually investigated (roughly: they weren't statisticians, but psychologists picked at a psychology convention, and the quiz question was not at all trivial, more like a tough exam test question, and not even vaguely similar or of the same "shape" as the story's riddle--making exactly zero elements of his anecdote actually truthful).

It is harder to check a book's bibliography, though. Sometimes the cited paper isn't publicly available, or sometimes the author cites a book you don't have (often their own books), and really in this day and age it's a little bit much to ask your audience to make a trip to the library just to check if an author isn't taking an extreme artistic license or even just making shit up.

I got a bit disillusioned after this tale. And definitely a lot more skeptical about "these types of book", you know the kind that weaves a lovely narrative "supported" by actual (pop) science research. The juicier the anecdotes, the more skeptical you should be.

And apparently this is still a pitfall even if the general premise of the book is right! (the core idea behind Black Swan I pretty much agree with--it just happens so that the very first reference I picked at random to check, turned out to be full of shit)

[0] One of Taleb's previous works, Fooled by Randomness, is roughly about the same topic, but goes into (a little bit) more technical detail. I enjoyed it a lot better. Also, it doesn't feel the need to make a stab at the French every third page or so (something that really puzzled me in Black Swan, maybe it was an in-joke between him and Mandelbrot?).

blowski• 13 years ago

Yep. We naturally get cancer, but it doesn't mean life would be worse if we were able to prevent it.

lmg643• 13 years ago

1) below is a link to the study being referenced - it is real:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.1992....

2) The study looked at 10 hrs daylight vs 16 hours of daylight. I wonder if "bi-phasic" sleep isn't just a quirk since the current consensus is humans need 7-9 hours of sleep a day. So, when you have less daylight - instead of sleeping continuously for 14 hours of night, you wake up at some point in between. The body simply does not need 14 hours of sleep per day.

If this were true - and referencing the paul graham-ism about meetings breaking up the day into segments too small to be useful - it is possible that artificial light allows us to compress the night hours such that they fit our maximum need for sleep, and also give us larger continuous blocks of time to use during the day. from this perspective, artificial light supports human evolution by making us more efficient (rather than representing some undiscovered health problem).

3) Also interesting to consider how the northern-most europeans would have adapted, given extended daylight for months at a time.

4) lastly - it's awesome to see we are getting health advice from medieval times. During the same period, people commonly drank alcohol almost 100% of their waking hours. Alcohol certainly affects my quality of sleep and duration. On a related note - a study of the effect of continuous alcohol consumption on judgment might explain a lot of the wacky behavior back then.

WalterSear4• 13 years ago

FWIW: the alcohol content of those drinks was very low indeed. I find it hard to imagine that there was much inebriation involved.

7952• 13 years ago

Scientific research would certainly be interesting; but I'm not sure what difference it would make. Beneficial outcomes are always going to be a matter of personal preference and convenience. This is worth trying for a few days, even without good evidence.

criley• 13 years ago

You can't change up your sleep for a few days and expect positive results. Even the participants in the study mentioned in the link took several weeks before their sleep habits changed appropriately.

gavanwoolery• 13 years ago

It is very real -- I am living proof. :) I choose my own hours for work, and often sleep twice, and my rhythm varies between being awake during the night and the day. I do think that not everybody is like this though.

chocolate_• 13 years ago

You just responded to a criticism of evidence being anecdotal with more anecdotal evidence.

LaGrange• 13 years ago

It's not the first time I hear about this — i.e. the book "Centuries of Childhood" by Philippe Ariès writes a bit about mentions of this habit in literature. If I remember correctly (which I may not), it mentions it was common for some period, but neither before or after.

In general I'd wish if people were more careful with general pronouncements like this — just because some people somewhere did something (say, hunt by running, eat only meat, eat only berries, sleep in two parts, sleep with the head hanging down, bake crackers, not cook anything, whatever) doesn't mean all humans did that until 5 years ago, nor does it mean it's a somehow best course for every single human dead or alive. Now, that it may be a good idea to try out (depending on specific idea, with specialist supervision maybe), but it might turn out horrible.

And I doubt anything like "optimal" sleep even exists, unless you start including additional conditions. You need work, you have to balance the need to sleep with the requirements of it (and some enjoyable jobs do start early), you might even a tendency to sleep too long for own comfort unless kept in check, and if you have apnea sleeping longer will only make things worse.

So, my annoyance here is mostly with the generalization made by the statement — not "we". Some other people, at some point in history, did, and wrote down all the awesome experiences they had while doing it.

xijuan• 13 years ago

This is a very interesting article!!!! I have been living alone for few months now.. My sleeping schedule starts to split into two equal halves of sleep!! I usually feel soo good after the second sleep.

SageRaven• 13 years ago

One summer in college, I sub-rented an apartment from a friend who was away for the summer. It was the first time in my life I had lived alone. I was working grounds crew at a dorm (relatively strenuous/active job). I'd get home around 4pm, have a snack, maybe watch some TV or listen to some tunes, then I'd just crash. I'd usually wake up after dark (being summer, between 8 and 10pm), eat dinner, then be up until 1 or 2am. Then I'd go to bed, then get up at 6am to be at work at 7am.

It was a great routine. Ever since career and family became part of my life, I've rarely ever had such peaceful moments in my life.

lucb1e• 13 years ago

Doesn't everyone know this by now? It pops up on HN at least twice a year.

legierski• 13 years ago

It does and it could more often. I don't think I know anyone who heard about it...

ghshephard• 13 years ago

I lived off the grid when I was in the ninth grade, and all we had for light was a kerosene lamp that put out about as much light as a pretty strong candle. It was hung up reasonably high, and so wasn't enough to read by, and, regardless, I slept up in the loft with my brother - and so the light didn't get up there (thought it did make for a nice warm spot on the plywood floor).

When it got dark - we went to sleep. And then we got up at 6:45sh to go catch the bus to school. I don't ever recall a "second sleep" or waking up after I fell asleep.

Maybe this doesn't apply to teenagers.

eiliant2• 13 years ago

Is this true?

superk• 13 years ago

When this happens to me – the hour or so I'm awake in the middle of the night is not a peaceful relaxing time – the night has this pessimistic quality to it: the assignment I'm working on is impossible, I'll never get it done, I'll lose my job, that pain in my side is likely cancer, etc.. with that on my mind I drift back into a turbulent sleep after a while, but when I wake to daylight all those problems seem trivial and I'm able to get up and cope with the day. If anyone else experiences something similar that's probably why medicating a full night of sleep is so widespread...

rhynie• 13 years ago

A while back I trained myself into the habit of sleeping in two cycles each night. I’m a night owl, and thought it would be a good way to get a full night’s sleep and still have the night owl lifestyle. After several months, I found myself feeling detached from the world.

The hour or two you get is literally between sleep cycles. During that nighttime, my mind would race and worry about the most useless things. The dreamlike state wouldn’t shut off cleanly and I could not concentrate, so that hour was never productive like I usually am during the night hours. It was impossible to learn anything, nothing would be retained. The second sleep cycle was always turbulent and I found myself waking up several times throughout. During the day, it felt like my emotions were muddled, like I was an automaton. That hour or two morphed into my only personal time, and the day became mindless, numb.

I considered this a failed experiment and re-trained myself back to a single sleep cycle. It was harder going back than it had been to split in the first place. After several months of ‘normal’ sleep I was back to having deep peaceful sleep. I was myself again during the day. I could learn and keep knowledge. The world was interesting again and I was engaging with it.

These were my experiences and expect it would be different for each individual.

mikecane• 13 years ago

Hmph. I would have thought the first thing people would do after waking from the first sleep is pee.

dbarlett• 13 years ago

The Ekirch book referred to is At Day's Close: Night in Times Past [1]. It covers much more than sleep patterns. We think of night as merely the absence of daylight, but in the past it was seen as a different world.

[1] http://www.amazon.com/At-Days-Close-Night-Times/dp/039332901...

desireco42• 13 years ago

Ha ha, be sure to mention this article to startup founders during the interview, see how far this gets you. This is the world in we live in, no life outside work, let alone sleep.

Livven• 13 years ago

It sounds plausible enough but I wonder why Ekirch (the historian referenced in the article) seems to be the only source for this theory? A quick look on Wikipedia [1] reveals no additional sources or scientific discussion either. It just seems a bit unlikely that such basic human behavior would be forgotten, only to be rediscovered by a single historian. Can anyone shed some light on how trustworthy this theory is?

BTW I don't have any evidence or bias against this. I'm just genuinely curious and a bit confused.

[1] http://en.wikipedia.org/wiki/Segmented_sleep

seandhi• 13 years ago

To add another anecdote, I usually do not have trouble sleeping through the night. Once I lay down, it takes awhile for me to fall asleep, but once I do, I sleep 8-9 hours without waking up. However, even when I awake, I still feel drowsy and not "rested".

Very recently, I started taking 3-6 mg of melatonin about thirty minutes before going to bed. I find that I fall asleep more more quickly, but I inevitably awake roughly four to five hours later, completely lucid. After a few minutes of being awake, I roll over and easily fall asleep again for another three to four hours. When the morning comes, I wake up feeling much more refreshed than I did when I slept continuously throughout the night.

I usually spend long nights in front of my computer, and from what I have read, melatonin production is reduced by the presence of blue light. I have started using Flux in addition to my melatonin intake. I can only guess that I am starting to enter a more "normal" sleep cycle.

aaron695• 13 years ago

I find this meme interesting.

It seems to me A. Roger Ekirch (a historian) used confusing text to create a medical theory then popularised it.

There is little to no one else saying it's true but somehow it's being spread as fact.

Equally it's interesting no one is refuting it. It's a popular theory I've heard a lot of people mention. If it is hogwash why is the medial community not jumping in and saying there is no evidence of this?

gcb0• 13 years ago

He tried to study that via old medical records and literature... But didn't try to see an Amish?

We used to sleep twice each night

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