Why Do We Need to Sleep?
February 12, 2018 4:33 AM   Subscribe

Biologists call this need “sleep pressure”: Stay up too late, build up sleep pressure. Feeling drowsy in the evenings? Of course you are—by being awake all day, you’ve been generating sleep pressure! But like “dark matter,” this is a name for something whose nature we do not yet understand. The more time you spend thinking about sleep pressure, the more it seems like a riddle game out of Tolkien: What builds up over the course of wakefulness, and disperses during sleep? Is it a timer? A molecule that accrues every day and needs to be flushed away? What is this metaphorical tally of hours, locked in some chamber of the brain, waiting to be wiped clean every night? [slAtlantic]
posted by ellieBOA (81 comments total) 69 users marked this as a favorite
 
This article is fascinating. Thank you for sharing it.


This poor mouse!
A few years ago, the group discovered a mouse that just could not seem to get rid of its sleep pressure. Its EEGs suggested it lived a life of snoozy exhaustion, and mice that had been engineered to carry its mutation showed the same symptoms.
posted by winna at 5:01 AM on February 12 [7 favorites]


Sleep is really a confounding mystery. We have seen how ruthless the forces of evolution are and yet there we are numb to the world around us, eyes closed because something, *something* is much more important. Or there is some basic fault in the system which cannot be worked around.

The best workaround is sleeping half the brain at a time, which birds sometimes do. It is less efficient it seems than full-brain sleep so it really is more of an emergency mode. But thats all we got.
posted by vacapinta at 5:23 AM on February 12 [4 favorites]


Not needing to sleep is one cyberpunky biohack I would embrace immediately, though with my luck I'd probably descend into madness after about three months not sleeping.
posted by MartinWisse at 5:37 AM on February 12 [6 favorites]


Really great article, I also enjoyed the jellyfish article linked in it as well.

I wonder if there has been any studies into certain conditions that cause the symptom of 'sleepiness'. And it probably differs for people. For me it's being in a moving vehicle, golf commentary on the television, soft sunlight and a cool breeze.
posted by like_neon at 5:57 AM on February 12 [2 favorites]


Its EEGs suggested it lived a life of snoozy exhaustion

It me.
posted by 41swans at 6:16 AM on February 12 [59 favorites]


I understand the feelings of that jellyfish.
posted by betweenthebars at 6:17 AM on February 12


See also: fatal familial insomnia, a genetic condition in which prion-mediated damage to the brain causes people to gradually lose the ability to acheive deep slow wave or REM sleep, resulting in progressive delirium and eventually death.
posted by dephlogisticated at 6:25 AM on February 12 [11 favorites]


Last time I talked to a doc at a sleep clinic, he told me cheerfully that no, they had no idea what sleep was for, and none of the theories really panned out. He was of the opinion that it was an evolutionary mistake and wasn't 'for' anything.

Personally, I think it's for repeatedly listening to the first ten minutes of podcasts or radio programmes.
posted by Devonian at 6:30 AM on February 12 [43 favorites]


This article stirred up some memories.

While in college I regularly “pulled all-nighters”; the results were interesting but I swore, after graduation, that I would never do it again.

Following hip replacement surgery I was intolerant of virtually all pain medications and was thus in such agony that for weeks I could not sleep, even for a minute. After a while I began hallucinating that Morpheus, who’d always existed as a kind of abstract concept in my head, was real and present. He had been my friend but had turned from me, lurking instead in shadowy corners, taunting me with his dark, enveloping cloak. I would plead for him to come to me and he would vanish.

About one month after the surgery my regular MD offered to trial yet another pain med, which I tolerated. The two hours of sleep the initial dose afforded were two of the sweetest I’ve ever spent on this planet.

I will never forget the desperate horror of the sleeplessness. It haunts me still.
posted by kinnakeet at 6:42 AM on February 12 [49 favorites]


I am reminded here of a story that I keep on planning to make a screenplay out of, but will likely never get to. Anyone who wants to make a run at it is welcome to it.
posted by Ipsifendus at 6:48 AM on February 12


What if sleep is the default state and the question is why must we wake?
posted by Mei's lost sandal at 6:50 AM on February 12 [60 favorites]


Roughly 16 hours a day of putting up with other people is enough as it is. I'll take the sleep, thanks (plus; dreams, yo!).
posted by The Card Cheat at 6:51 AM on February 12 [19 favorites]


The CEO of the company where I work has sort of adopted one of my colleagues as his unofficial assistant. My colleage recently shared with me a "joke" that the CEO told him - "see, people like us? We don't take vacations."

....Maybe the function of sleep is to make hyper Type-A dudes like that, who don't give themselves a break, actually stop and rest for a second because their body forcing them to lose consciousness is the only way it would happen.
posted by EmpressCallipygos at 6:52 AM on February 12 [5 favorites]


The longest I went without sleep was four days when I was moving across multiple states after college.

At day four I was seeing shadow people out of the corner of my eyes and was subject to violent irrational fits of rage and hilarity for no cause. It was not fun and I do not recommend.

Also I would not want to get rid of sleep because it is one of my purest pleasures in this world.
posted by winna at 6:52 AM on February 12 [10 favorites]


> EmpressCallipygos:
"....Maybe the function of sleep is to make hyper Type-A dudes like that, who don't give themselves a break, actually stop and rest for a second because their body forcing them to lose consciousness is the only way it would happen."

The "unofficial assistant" is more likely to clock the CEO with a baseball bat and bring on the unconsciousness themselves!
posted by chavenet at 6:55 AM on February 12 [1 favorite]


IANAbrain scientist, but....

I read somewhere that some scientists had a good theory as to why we need to sleep, that seems to fit the pattern mentioned in the article. That the mechanisms for removing cellular waste from the cells into the blood that is ordinarily flushed away from cells throughout the body don't work for the brain, because of the blood-brain barrier. This waste is instead dumped into the cerebrospinal fluid that permeates the brain, where it builds up.

This fluid circulates in the brain, and there are places where the waste from it is collected into the blood for eventual removal at the kidneys, but all those neurons get in the way of its efficient flow. During deep sleep, some (all?) of the neurons physically contract in size, allowing the fluid to circulate better but hindering the function of those neurons. Importantly, the waste-removal mechanisms work even while you're awake, but only about 10% as well. Eventually the presence of too much waste causes cells to not be able to evacuate their own waste, and supposedly that's what causes sleep pressure.

Did this research exist or did I (heh) just dream it? I dunno, it's been two or three years since I saw it.
posted by JHarris at 6:55 AM on February 12 [23 favorites]


One idea is that sleep is necessary for clearing beta-amyloids that build up during waking hours. Beta-amyloid build-up is also associated with Alzheimer's disease, which I guess yields the interpretation that Alzheimer's patients act as though they are really, really, really sleepy.
posted by logicpunk at 6:57 AM on February 12 [3 favorites]


Death would be a lot more terrifying if we never slept.
posted by Devonian at 6:58 AM on February 12 [20 favorites]


I will never forget the desperate horror of the sleeplessness. It haunts me still.

I believe that depression with insomnia explains a lot of suicides.
posted by thelonius at 7:00 AM on February 12 [14 favorites]


Did this research exist or did I (heh) just dream it? I dunno, it's been two or three years since I saw it

I've heard this theory as well, but it has a few problems. It's definitely the case that we "clean our brains out during sleep. but this alone doesn't explain the different stages in sleep, or the importance of achieving REM sleep, for example. Also why couldn't we achieve this cleaning in 10 minute bursts throughout the day, which would be more efficient from a survival standpoint?
posted by dis_integration at 7:00 AM on February 12 [3 favorites]


Longest I've gone without sleep, I helped some friends move to New Orleans. We partied late into the night on Friday, packed up EVERYTHING from two apartments Saturday, then started driving.

We were somewhere in Mississippi, on the edge of the swamp, when the sleeplessness began to take hold. Highway construction equipment became ancient megafauna. After swerving to miss the second backhoe brachiosaur, it was too much, and I had to pull over for rest.
posted by notsnot at 7:03 AM on February 12 [6 favorites]


plus; dreams, yo!

Srsly. The other night, I dreamed that I had moved into an apartment, and the previous tenant had left behind racks with CDs. I examined them; the first was titled "You Can't Sue Captain James T. Kirk For A Bad Trip". I got that for free!

I still miss Slow Wave
posted by thelonius at 7:03 AM on February 12 [19 favorites]


Also why couldn't we achieve this cleaning in 10 minute bursts throughout the day, which would be more efficient from a survival standpoint?

My guess is that sleep, because it is a universal function, eventually evolved so that other necessary body functions came to rely on it too. If everyone has a period of time where they have to be unconscious, it is evolutionarily advantageous to use that time to do other things elsewhere in the body, and eventually it got to be so that a number of systems relied on each other and made it difficult to evolve away. Kind of a local minima on the graph.

I dunno. Is a guess. As for the need for different stages, maybe cells need a running start to contract? Maybe fairies do it. I think fairies explain everything.
posted by JHarris at 7:06 AM on February 12 [2 favorites]


I prefer sleep to wakefulness, actually. In my dreams, I'm normal.
posted by Ray Walston, Luck Dragon at 7:16 AM on February 12 [1 favorite]


What would be really nice is some exercise, method or drug that kicked that pressure to the max sometime before midnight rather than waiting until two or three AM.
posted by sammyo at 7:17 AM on February 12 [8 favorites]


I prefer sleep to wakefulness, actually. In my dreams, I'm normal.
Does that mean you're a viking when awake?
posted by Hal Mumkin at 7:22 AM on February 12 [11 favorites]


Sleep is really a confounding mystery. We have seen how ruthless the forces of evolution are and yet there we are numb to the world around us, eyes closed because something, *something* is much more important. Or there is some basic fault in the system which cannot be worked around.

My guess is that sleep, because it is a universal function, eventually evolved so that other necessary body functions came to rely on it too.

I always assumed that sleep didn't evolve - everything was always asleep, and then at some point consciousness evolved, but it was strenuous/resource-heavy, so no creature manages it for more than a few hours at a time.
posted by kersplunk at 7:24 AM on February 12 [24 favorites]


I actually read somewhere that REM helps process memory. I'll buy it; the times when I've been sleep-deprived are also the times that I've been most brain-foggy.

I also read something else cool about REM state. There was a time I was coming off a super-charged schedule of theater, and had realized that I was suffering from sleep deprivation (I was getting only 6 hours of sleep). I took a break from theater and made a conscious effort to get 8 hours of sleep.

Within a week, I started having really vivid, frequent dreams. It was unusual enough that I did a little REM research; why was I having more dreams? That's where I learned about the memory-processing thing - but I also learned something that sort of explained the uptick in frequency (for me anyway). Apparently - there is a regular rhythm to how many times per night your brain goes into REM state. And - if you start regularly suffering sleep loss, one of the ways your body tries to compensate is by adjusting that REM cycle. So, for instance, if you usually get 8 hours and your body goes into REM once an hour, but then you start getting only 6 hours, gradually your body will start trying to get into REM every 40 minutes or so, to try to catch up.

I figured, then, that what was happening with my suddenly remembering more dreams was that my body was still on the stepped-up schedule and hadn't adjusted back yet - which was then increasing the likelihood that I'd wake up in the middle of REM state, and thus remember a dream. Within a few weeks I was back to a more normal schedule and dream frequency again, so I think there's something to that.

...Had some kind of weird dream last night, ironically, but I don't really remember the details now - it somehow involved a mishmash of Kevin Costner and tennis balls being thrown out the window of a restaurant or something.
posted by EmpressCallipygos at 7:31 AM on February 12 [4 favorites]


I'm surprised the article didn't address the profound sleepless that new parents endure. My first born was a terrible sleeper and since I was nursing, her schedule was my schedule. For weeks I never slept for more than 2-3 hours a straight and I was simple from the lack of sleep. When she was 8 weeks old, I woke up, checked the clock, and discovered I had been asleep for hours (iirc, abt 4). My first thought was, of course, oh my god something's wrong! I immediately recognized I couldn't possibly handle a tragedy in my current state of exhaustion and I went back to sleep.

FYI, both she and her brother are now 20-somethings, i.e., they survived despite my obvious inadequacies.
posted by she's not there at 7:36 AM on February 12 [15 favorites]


Doesn't sleep also help recover from physical exhaustion and injury? I don't think 10 minute (or even like 2 hour) increments are enough recovery time for the short-burst physical action that tons of animals rely on.
posted by The_Vegetables at 7:45 AM on February 12 [1 favorite]


I liked the idea that animals wake up from hibernation to sleep.

I need a real 8-9 hours a night, and though I wish it were a bit less, I really enjoy sleeping.
posted by jeather at 7:47 AM on February 12 [3 favorites]


Devonian: He was of the opinion that it was an evolutionary mistake and wasn't 'for' anything.

I've read the same thing about fever; apparently no-one has yet demonstrated a clear survival advantage for it, but it's conserved across most animal species. The fact that it's so widely conserved, though, surely says that it's important. Surely?

dis_integration: Also why couldn't we achieve this cleaning in 10 minute bursts throughout the day, which would be more efficient from a survival standpoint?

Some animals, like horses and giraffes, sleep exactly like that.

In mammals, as touched on in the article, predators tend to get a lot of sleep while prey gets very little. I suspect that access to a burrow or house of some kind makes a difference, too; if you're a gazelle on the open plain, it pays to be awake as much as possible.
posted by clawsoon at 8:13 AM on February 12 [3 favorites]


We were somewhere in Mississippi, on the edge of the swamp, when the sleeplessness began to take hold. Highway construction equipment became ancient megafauna.

We can't stop here. This is CAT country.
posted by Mr. Bad Example at 8:19 AM on February 12 [24 favorites]



Imagine how much healthier our society would be if people could get enough sleep?

2 sleep anecdotes:

1. I participated in one of those studies where you prune back your rest hours (time you are allowed to stop moving) every day until you hit the point where you start hallucinating while awake. I was able to survive on far less sleep than normal for most of a year afterwards, but the training process was gruesome.

2. Insomnia is a curse I wouldn't wish on anyone. In the throes of a bad bout of insomnia I broke a finger and a toe in different incidents and it just didn't matter because it was nowhere as bad as the lack of sleep.
posted by LegallyBread at 8:23 AM on February 12 [5 favorites]


I enjoy sleeping - when my anxiety, the neighbors making random twanging noises upstairs, the housemate (another erratic sleeper) cooking, however quietly, at 3:00 am, et cetera, aren't, singley or in a team effort, destroying my ability to do so.

The following day, dragging blearily about, I curse evolution.

The biological imperative to sleep is not kind to those of us who are not good at it.
posted by Armed Only With Hubris at 8:24 AM on February 12 [3 favorites]


What if sleep is the default state and the question is why must we wake?

Once upon a time, I, Chuang Chou, dreamt I was a butterfly, fluttering hither and thither, to all intents and purposes a butterfly. I was conscious only of my happiness as a butterfly, unaware that I was Chou. Soon I awaked, and there I was, veritably myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man. Between a man and a butterfly there is necessarily a distinction. The transition is called the transformation of material things.

- Zhuangzi (Chuang Chou)
posted by kokaku at 8:31 AM on February 12 [14 favorites]


If you're going to go to some evolutionary argument, surely the day/night cycle helps explain sleep? When the sun is gone there's no energy coming in for photosynthesis, no light for vision, no warmth. It seems natural that creatures would evolve to be less active in this period, except for those nocturnal animals that evolve to take advantage of the quiet time everyone else is asleep.

At least that's my best college try at a hypothesis. It seems to have some testable implications.
posted by Nelson at 8:44 AM on February 12 [5 favorites]


> The fact that it's so widely conserved, though, surely says that it's important. Surely?

Of course it does. It's only the modern extreme form of scientism, which is a form of insanity, that says confidently "If we don't know what it's for, it's useless and can be done away with!" As if we already know everything important. (They thought that at the end of the 19th century, too.)
posted by languagehat at 8:49 AM on February 12 [4 favorites]


When the sun is gone there's no energy coming in for photosynthesis, no light for vision, no warmth. It seems natural that creatures would evolve to be less active in this period, except for those nocturnal animals that evolve to take advantage of the quiet time everyone else is asleep

Oddly, it is nocturnal animals that need the most sleep.
posted by vacapinta at 8:53 AM on February 12


The question gets it backward. Sleep is a low-energy state. The question is not why we sleep, but why we are ever awake. And that's a lot more tractable: animals need to have a period of activity where they can satisfy the requirements for survival and reproduction. Making that period any longer than it would need to be would be wasteful and bad design. It makes sense to shut the system down as often as possible. Certain environmental regularities make for sensible built-in schedules to go online. So, for lots of animals, it's sleep at night, hibernation in the winter; but of course different niches and different survival demands call for different schedules of wakefulness.

(Once you've got that period of downtime, it can be used for quiet processes such as memory consolidation or whatever dreaming is for... there are genuine questions about these. But dreaming shouldn't be confused with sleep. There's a difference between asking what sleep is for and what the processes that occur during sleep are for. Probably not all animals that sleep also dream.)
posted by painquale at 8:57 AM on February 12 [7 favorites]


I can’t remember the last time I felt naturally tired before around 2am. I regularly either sleep through my alarms or else get 5-6 hours of sleep on weeknights and then 10-14 on weekends. Several months ago I stumbled across the concept of circadian rhythm disorders and I literally cried a little bit – maybe I wasn’t a lazy piece of crap, maybe I had delayed sleep phase disorder!

Reading up on circadian rhythm disorders, I ran across a lot of info about sleep pressure. Unlike this article, those sites didn’t tend to focus on why we need sleep, but on the systems that regulate that need (or fail to). One of the most critical ones is exposure to light – bright blue light in the morning, dim orange light followed by darkness in the evenings (in line with what we’d experience if our only source of light was from the sky).

I had to wait a few months for a sleep doctor appointment. The doc told me I had ‘classic’ DSPD and prescribed the following: light therapy goggles for 30 minutes at 8am every morning (even weekends, even if I go back to sleep afterward), orange-tinted goggles after 8pm to block blue light, 1mg of melatonin nightly at 8pm, bed at midnight.

It’s been about a week so far, and I’m still working on getting perfectly compliant with the regimen (partly because I’m still catching up on sleep), but OH MY GOD. I’m getting SLEEPY IN THE EVENINGS. Like, BEFORE MIDNIGHT. I’m going to bed at midnight and FALLING ASLEEP without an hour+ of racing thoughts and tossing and turning.
posted by showbiz_liz at 9:00 AM on February 12 [26 favorites]


The question is not why we sleep, but why we are ever awake.

Because if we were never awake, we couldn't write papers about why we need to sleep.
posted by JHarris at 9:01 AM on February 12 [2 favorites]


dspd guy here. everyone else, imagine being badly jet-lagged. every day, for 30 years.

ok, not *every* day. maybe 10-20 mornings each year i wake up feeling refreshed. today is one of those days!!!!

i swear, it's night and day (heh). if there were a street drug that made me feel like i do right now, i would be a dangerous man.

it sorta explains how normal people are so cheerful and get so much shit done.
posted by j_curiouser at 9:16 AM on February 12 [8 favorites]


i swear, it's night and day (heh). if there were a street drug that made me feel like i do right now, i would be a dangerous man.

Not a street drug, but if you have wakefulness problems, you might be able to get a scrip for it: Modafinil.

I've used it offlabel and it is fantastic stuff, promoting wakefulness and alertness but not interfering with my sleep.
posted by dis_integration at 9:26 AM on February 12 [2 favorites]


Now I'm wondering about animals at the bottom of the deepest ocean or lightless caves - do they sleep?
posted by bonobothegreat at 9:47 AM on February 12


Now I'm wondering about animals at the bottom of the deepest ocean or lightless caves - do they sleep?

I guess the deep ocean fish do the same thing as the other fish do.

Lightless caves is easier because there's not much life in those things. Caves are as dark as I imagine the bottom of the ocean to be, so no plants/algae grow there and without the top layer droping food down there's nothing to eat and almost no animal life. I did once feel bad for a cenote fish that followed our lights 2000ft inside the cave tunnels in Mexico, he wasn't with us when we got out, I hope he got to follow other divers to the surface.
posted by WaterAndPixels at 9:58 AM on February 12 [1 favorite]


Am I the only one who is sometimes weirded out by the idea of sleep? Of having to, well, disappear, and then be forced to view dreams that you have no control over?

And are there people my age or older (I'm 57) who actually sleep straight through the night? I always wake up at least two or three times a night, and have done so for as long as I can remember.

But then I'm lucky enough to need less sleep than most people - I feel refreshed on 7 hours a night, and can get by for extended periods on 6.
posted by tallmiddleagedgeek at 10:11 AM on February 12 [6 favorites]


In order to fall asleep, you must (almost always) PRETEND to be asleep first. WTF
posted by Brocktoon at 10:12 AM on February 12 [9 favorites]




Am I the only one who is sometimes weirded out by the idea of sleep? Of having to, well, disappear, and then be forced to view dreams that you have no control over?

I'm often irritated by it- I have better things to do!
posted by Pope Guilty at 10:50 AM on February 12


He was of the opinion that it was an evolutionary mistake and wasn't 'for' anything.

An evolutionary mistake that's universal across mammals, birds, reptiles, fish, and invertebrates? I call shenanigans. If that were true, evolution must've dropped the ball, not once or twice, but thousands of times across creatures adapted to wildly different environments, ranging in size from ants to whales.

If it's a "mistake," serving no useful purpose, it's worthy of even more study as a genetic feature that the majority of living things on the planet couldn't shake.
posted by ErisLordFreedom at 11:10 AM on February 12 [13 favorites]


Now I'm wondering about animals at the bottom of the deepest ocean or lightless caves - do they sleep?

I can't answer this specifically, but in humans anyway, it's not that darkness = sleep and light = wakefulness exactly; it's that we have internal sleep/wake clocks which don't necessarily run on a perfect night/day cycle without some external reenforcement.

I didn't know this until recently, but among completely blind people, over half of them have non-24-hour sleep/wake disorder. Some peoples' internal clocks say that a complete sleep/wake cycle ought to be, say, 22 hours long, or 27 hours long - but with the external stimulus of light, human bodies are able (with greater or lesser degrees of success) to adjust to a 24-hour cycle anyway. Blind people can't do that, and it can be absolutely debilitating.
posted by showbiz_liz at 11:48 AM on February 12 [5 favorites]


has somebody said this already? probably.

We've got it mostly backwards in this thread, and through most of the so-called modern world. We do all of our waking stuff (hunting, gathering, plundering, building and maintaining vast and complex societies and civilizations) in order to allow for extended phases of not sleep so much as the conjuring of cosmic stuff with our dreaming. What do you think all that imponderable vastness is out there in the universe? That's the stuff of our dreams.

I know all of this because I dreamed it once.
posted by philip-random at 11:49 AM on February 12 [1 favorite]


omg those external regulatory cues are called zeitgebers how delightful
posted by showbiz_liz at 11:55 AM on February 12


Yep, Zeitgeber is one of the first terms you learn in a circadian lab. Also you learn to never, ever, ever, EVER let any light into the room after lights out, under pain of banishment, and it makes it pretty much impossible to work in a non-circadian lab where people don't care about things like the half inch gap under the door that lets in light or the light in the hallway that is always on 24/7 and shines right into the housing room through a window in the door or what have you. Yay circadian biology!

"In fact, a group of chemists at the institute at Tsukuba is collaborating with a drug company in an investigation of the potential of orexin mimics for treatment." Great, now that I'm out of the field, they are finally coming up with an orexin/hypocretin agonist? The antagonists are kind of shitty (extremely poor solubility, but they work) but so far no one has made a decent agonist. I worked on orexin/hypocretin for like 15-16 years... it's a weird peptide, found only in vertebrates, critical for sleep/wake stability, and for whatever reason it is also involved (to a greater or lesser degree) in a ridiculous number of other seemingly unrelated processes. Feeding, sleep/wake, hypoxic response, reproduction, stress response, sleep apnea, it's a long and weird list. Point to a part of the brain, odds are it gets orexinergic input. (I know, I looked. Pretty much everywhere.)
posted by caution live frogs at 12:25 PM on February 12 [6 favorites]


Oh man, sleep has been a problem throughout my life, and this was very interesting, but I feel like I just have more questions now.

I wonder why we hallucinate when we're sleep-deprived. I still remember sitting in math class in 7th grade and seeing that someone had spray-painted a drawing of a jester on the floor, then realizing that I was just very tired, and that there was nothing there. I've had similar experiences over the years during bouts of insomnia. What causes this?

It's the same thing as when you're falling asleep and start to get weird. I've fallen asleep while having conversations with people, and started saying weird, unrelated things to them (which even I would notice before politely excusing myself to go to bed). I feel like I've seen other people do it, too. I thought you weren't supposed to start dreaming until you'd been asleep for a while, so why is it that some people seem to start dreaming instantly?

Also, why do people sometimes need to sleep so much when they have headaches? Especially migraines. I accidentally slept in this morning, and I was wondering why I was so tired, and it was only after I'd been up for a little bit that I noticed I had a migraine. That happens a lot: I'll get a migraine, and my body will feel so weak and tired that I have to go sleep. Similar thing with my girlfriend: sleep is the only thing she can do if she gets a migraine. Is the physical tiredness the result of having a migraine, or do I have it backwards, and I have a migraine because of whatever is making me so physically tired?
posted by shapes that haunt the dusk at 12:27 PM on February 12 [1 favorite]


Crikey. Sleep. What a concept. Generally I am lucky to get around 4 hours of sleep. I try to block sleep into 90 minutes increments, as that is the average length of a sleep cycle. I can come home COMPLETELY exhausted after 24 hours plus awake and after a few minutes, not be able to sleep at all for hours. I am a firm believer that I am a CRY1 mutant at this point as this has persisted pretty much my whole life.

My standing one time record (during my amateur pharmaceutical days was five days without sleep, as I got locked into a cycle of use/not get any sleep/go to work/come home/use). I was hallucinating up a storm. I also ate almost nothing and had VERY little fluid intake. It was horrible.
posted by Samizdata at 12:27 PM on February 12 [1 favorite]


One thing to remember is that bodies are giant networks that need to synchronize to get anything done. A sleep dependence means an available sync signal on a ~24 hour scale, removing the dependence means every system dependent on it needs to find something else to sync to.

Needs to find the same thing to sync to.

Across bodies, if sexual reproduction is your thing.

Oh, and whatever you're trying to synchronize needs to work while mobile and awake, for whatever that means for you.

I could imagine multiple sleep signals co-evolving. Given "nerves that fire together wire together" though, they'd just reinforce the existing sleep response. Not surprised we're stuck with this.

Wonder what the most complex organism is that shows no sleep response.
posted by effugas at 12:53 PM on February 12


Apparently C. Elegans shows sleep, nobody seems to have looked at Pratylenchus coffeae (smallest animal genome), and clocks/dormancy/enhanced behavior on restoration have been detected in bacteria, which do all sorts of coordination with eachother even if they're not multicellular organisms per se.

Interesting.
posted by effugas at 1:03 PM on February 12 [1 favorite]


Yeah, I get a mutation and my superpower is insomnia and exhaustion. Yay me?
posted by Samizdata at 1:11 PM on February 12 [1 favorite]


The idea that it's an evolutionary mistake is silly as ErisLordFreedom said above. Even the idea that is just to keep animals quiet when they aren't gathering food doesn't make sense, it would be more safe and efficient to have them wired to be quiet but conscious so they aren't hunted. And you would expect animals that are active 24 hours, that in some cases *have* to be active 24 hours or die (some kinds of sharks, long distance flyers) to have evolved away from it, but instead they work by having only sections of the brain go into sleep mode at any given time.

It's pretty clearly something required on a very basic biochemical level and for whatever it is, sleep is apparently a very efficient solution, thus the lack of alternate paths.
posted by tavella at 1:44 PM on February 12 [6 favorites]


my migraine opinion is that migraines actually fucking kill you and the subsequent exhaustion is your body grimly clawing its way back from death
posted by poffin boffin at 2:33 PM on February 12 [7 favorites]


Whenever I have unstructured days, I sleep on the same schedule as my cats— about 20 hours a day with short wakeful periods to eat and excrete. Cats do a couple laps around the house and I put the laundry in the washer and move it to the dryer during our next wake time. Unlike the cats, I lose all my muscle tone is I do it more than a couple days at a time. I envy cats their ability to stay in shape only moving a few hectic times of day. Evolution is weird.
posted by a humble nudibranch at 2:33 PM on February 12 [3 favorites]


Yeah, the point that given _all_ the opportunities and evolutionary niches, that sleep sticks around, does point to some pretty basic biochemistry.
posted by effugas at 2:34 PM on February 12 [1 favorite]




I will never forget the desperate horror of the sleeplessness. It haunts me still.

I believe that depression with insomnia explains a lot of suicides.


Having experienced lack of sleep and restful sleep due to pain and depression for many years, I can agree with this. Having kicked depression enough that is was no longer a constant draining shadow (pain reduction seemingly unrelated) def severely decreased my bouts of suicidal ideation to zero.

However when I experience pain or sleeplessness in less than a week but still constant bouts over that week, suicdal thoughts take over my skeleton and I’m back to bad. But it’s enougg to remember I have felt good and I will again. I warn my partner if it continues longer than I feel it should or I can’t shake it, I’ll need them to help me get help. They step up wellness and mental health pings till I tell them I’ve shaken it.

Longest bad period was three months with a pinched nerve about five years after I stopped inhaling and exhaling long term depression... I took a few me days off from work and actually broke out in hives till the nerve got fully unpinkched (via chiropractic adjustment that was a true last resort as I class it with astrology and homeopathic cures).

Right now I’m lying in bed with pain meds, hoping for some rest once they kick in. I’ve gotten zero work done but I’m going to force myself tomorrow as this usually lets up by day five (endometriosis pain stoopid Frankenbody)
posted by ute there it is at 3:38 PM on February 12 [5 favorites]


Making that period any longer than it would need to be would be wasteful and bad design. It makes sense to shut the system down as often as possible.

I'm skeptical that the answer is so simple, because consciousness is not that energetically expensive, and human culture since the development of agriculture (probably since the development of trade and weapons) would have afforded enormous reproductive advantages to anyone who could remain conscious and productive 24/7. That's over 200 generations, long enough for shortened sleep cycles to have proliferated if it was just a matter of conservation.
posted by Coventry at 4:58 PM on February 12


Coventry,

Anything conserved across apparently all animal life laughs at 200 generations. Also it's not like we've had nighttime light for that long.
posted by effugas at 5:10 PM on February 12


Sure, but that's further evidence that there's more going on than simple conservation of energy. There must be many niches where not having to sleep would be a huge advantage.
posted by Coventry at 5:41 PM on February 12


honestly whatever theory that was presented upthread which was basically "your brain needs to poop" is the best one because of the horrible infuriating frustrating parallels between medication induced insomnia and constipation
posted by poffin boffin at 6:46 PM on February 12 [11 favorites]


I participated in one of those studies where you prune back your rest hours (time you are allowed to stop moving) every day until you hit the point where you start hallucinating while awake. I was able to survive on far less sleep than normal for most of a year afterwards, but the training process was gruesome.

Aka early parenthood
posted by KateViolet at 7:25 PM on February 12 [1 favorite]


One of the most critical ones is exposure to light – bright blue light in the morning, dim orange light followed by darkness in the evenings (in line with what we’d experience if our only source of light was from the sky).

Green light as well: 1,2.

Software to turn down the blue (and green) pixels:

Flux (for Windows Mac Linux iPhone/iPad Android.)

I think some programs will turn down the green pixels further than flux. I have an old copy of redscreen for osx, but it may not be available any more. On debian just type:
$ sudo apt-get install redshift

Orange goggles are $10 - $33. (As I wear glasses, I'm thinking of getting orange wraparound sunglasses.)
posted by sebastienbailard at 1:08 AM on February 13 [2 favorites]


natural selection works the other way too
posted by thelonius at 3:01 AM on February 13




My son didn't sleep more than four hours at a stretch until he was three or four (it's a haze). You'd think evolution would have weeded those kind of terrible behaviors out. It's a wonder I didn't eat him.
posted by The corpse in the library at 8:28 AM on February 13 [6 favorites]


Sleepless crying baby meat is a great nightcap if you season it with ambien.
posted by Coventry at 10:25 AM on February 13 [3 favorites]


Dang, that is a rough chuckle, dude
posted by Ray Walston, Luck Dragon at 2:00 PM on February 13 [1 favorite]


That's an interesting study in two ways to tell the same joke.
posted by The corpse in the library at 4:51 PM on February 13


If we didn't sleep we wouldn't have beds and then where would I hide when the anxiety monster comes to play?
posted by twilightlost at 7:54 PM on February 13


In order to fall asleep, you must (almost always) PRETEND to be asleep first. WTF

This one's tough for me and I never really understood how to do that until recently. It took me way too long to find this comment from the most recent FPP about sleep. I think the cognitive shuffle may be changing my life for the better. Though I haven't really bothered with the picturing things part of it; I just try to come up with a bunch of random words starting with a letter and it seems to work well for me. Channeling my brain's ability to come up with nonsense, but for a good cause.
posted by asperity at 9:10 AM on February 16


I will never forget the desperate horror of the sleeplessness. It haunts me still.

I believe that depression with insomnia explains a lot of suicides.


It certainly fits. A decade or so ago I went through a very, very rough patch. I was on a bit of a cocktail of antidepressants and anxiety medication. Severe akathisia during the day, and total insomnia during the night. Many of those sleepless, pickled nights resulted in quite horrifying hallucinations.

The one I remember most clearly is: my computer was near my bed, screen off, but the red laser from the mouse still discernible. In the pitch black that red light morphed into two glowing red eyes, and as my vision adjusted resolved into one of those hideous cymbal-clashing wind-up monkeys that are so common in horror movies. When it appeared to be winding up to commence clashing its cymbals, and when the environment around it likewise started coming alive in unpleasant ways, I had a massive panic attack, leapt out of bed, and ran outside. For a long time after that I was only ever able to get to sleep by drinking myself unconscious.

Point is: get your sleep, folks. No devices or bright screens three hours before bed. No caffeine after 4. Camomile tea helps.
posted by turbid dahlia at 1:58 PM on February 18 [1 favorite]


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