
We used to sleep twice each night - anigbrowl
http://www.delanceyplace.com/view_archives.php?2137
======
mech4bg
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.

~~~
lmg643
1) below is a link to the study being referenced - it is real:

[http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.1992....](http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.1992.tb00019.x/abstract)

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.

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

~~~
merlincorey
Indeed, everyone drank alcohol, and most of us are genetically predisposed to
having some affinity for doing so currently, due to the simple fact that beer
was sterile, and water made you sick. See: How Beer Saved the World

------
chubot
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.

~~~
WA
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
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…

~~~
the_economist
Our relationships with the sun are deeply disturbed and this is likely
responsible for many ailments, mental and physical, that we suffer from.

Our circadian rhythms are regulated by sunlight. More specifically, the pineal
gland in the brain suppresses melatonin when the retina is exposed to natural
sunlight. This allows for a huge melatonin surge at night, putting you to
sleep and telling the body to perform its nighttime functions. When you aren't
exposed to natural light during the day, your pineal brands produce melatonin
when they should not be doing so, leading to all sorts of problems.

To make matters worse, even looking at the sun through a window won't work;
enough spectrum is blocked that melatonin production continues.

tl;dr; If you want to optimize health and sleep, work outside (in the shade)
as often as possible.

~~~
keithpeter
OK, I live at 53 degrees North, so of course we have short winter days and
long summer days. Any reference on the longer cycle regulation of melatonin?

I've noticed that I just _do more_ when the longer days return...

~~~
the_economist
There is some thought that even an hour outside at noon can regulate your
melatonin cycle. I would at least try that, coupled with less artificial light
after dark.

------
davidroberts
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!

------
rayiner
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
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.

------
ghshephard
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.

------
kanamekun
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
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.

------
mbenjaminsmith
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.

------
superk
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
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.

------
dougk16
More evidence perhaps: <http://en.wikipedia.org/wiki/Midnight_Office>

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

------
cfeduke
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
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.

------
zissou
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...](http://books.google.com/ngrams/graph?content=nap&year_start=1800&year_end=2000&corpus=15&smoothing=3)

~~~
philwelch
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."

~~~
mgkimsal
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.

~~~
philwelch
Troops sleep whenever they can. Combat doesn't keep a schedule.

~~~
mgkimsal
Understood, but one might say that to leadership - Churchill - the war isn't
slowing down sir - taking a nap when people's lives are on the line probably
didn't look all that hot to many people.

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

------
zachlatta
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.

~~~
grannyg00se
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").

~~~
WalterSear
Except we have evidence that you can sleep too much.

~~~
firefoxman1
With adequate access to natural light, it's pretty hard to oversleep if you
follow your body's natural schedule. As soon as light hits your (still closed)
eyes, your brain scales back melotonin production and raises your body's
temperature, which is what wakes you up. The opposite happens when the sun
goes down and you aren't around artificial light.

~~~
vidarh
Given how vastly different lengths the night have depending on how far
North/South you go, that might be so but it's a solution that won't for for a
whole lot of people without artificially simulating a shorter night.

------
furyofantares
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
so says the article.

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

------
Livven
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>

------
desireco42
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.

------
Elv13
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
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.

------
lucb1e
Doesn't everyone know this by now? It pops up on HN at least twice a year.

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

------
seandhi
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.

------
mattm
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.

------
hkmurakami
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>

~~~
anigbrowl
HN strikes again! Cahced:

[http://webcache.googleusercontent.com/search?q=cache:IAiep0K...](http://webcache.googleusercontent.com/search?q=cache:IAiep0KBjPgJ:www.delanceyplace.com/view_archives.php%3F2137+&cd=1&hl=en&ct=clnk&gl=us)

------
philmcc
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)

------
dbarlett
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...](http://www.amazon.com/At-Days-Close-Night-
Times/dp/0393329011)

------
gcb0
He tried to study that via old medical records and literature... But didn't
try to see an Amish?

------
xijuan
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
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.

------
onlehuong
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.

~~~
anigbrowl
I love you cupcake :)

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

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

------
eiliant
Is this true?

------
aaron695
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?

------
badgar
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.

~~~
homeomorphic
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.

~~~
anigbrowl
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.

~~~
homeomorphic
It's been like this all my life, or as long as I can remember. The waking
thing doesn't happen too often - once a month or so - so it's not a big
problem. Thanks for your concern, though.

~~~
ldng
Well maybe you should embrace it then. Wake up, focus on doing something and
back to sleep. After reading that article, I would definitely try that.

