Sleep Flushes Toxins from the Brain

http://www.bbc.co.uk/news/health-24567412

by anishkothari • 13 years ago

252 93 13 years ago

bbc.co.uk

tokenadult• 13 years ago

Science Now, the news service affiliated with the journal Science, has a write-up on this report,

http://news.sciencemag.org/brain-behavior/2013/10/sleep-ulti...

and that links to the abstract

http://www.sciencemag.org/content/342/6156/373

of the published study itself.

elwell• 13 years ago

I definitely prefer direct links to research publications over news outlets.

anishkothari• 13 years ago

Thank you for these links, I wish the BBC article included them. Here's the press release from the University of Rochester, where the study was conducted:

http://www.urmc.rochester.edu/news/story/index.cfm?id=3956

tannerc• 13 years ago

Can anyone with better knowledge of such things explain why this has to occur during sleep? Is there just too much going on during the day to dedicate physical and mental resources to this type of cleaning?

jared3144• 13 years ago

[Dr Nedergaard] told the BBC: "This is purely speculation, but it looks like the brain is losing a lot of energy when pumping water across the brain and that is probably incompatible with processing information."

XorNot• 13 years ago

The question on everyone's mind now is, can you bypass that need?

mey• 13 years ago

My reaction to this, it is very important to by well hydrated when sleeping.

scotty792• 13 years ago

I wonder if sleepwalkers have this cleanup system working normally just and the part that supposed to shut off the muscles is not working properly.

jared3144• 13 years ago

That was my understanding of both sleep walking and sleep paralysis. The parts of your brain that activate during REM dreaming would cause you hurt yourself if GABA and glycine didn't shut off your muscles, thus putting your body into the bio-equivalent of park.

j-g-faustus2• 13 years ago

I have no better knowledge, just parsing the reports: The cleanup is more effective during sleep because the channels that transport waste from the brain expand 60% in volume, and the brain cells themselves shrink by a similar amount to make room.

I suppose that the brain cells can't shrink that much while retaining their full function.

comrade_ogilvy4• 13 years ago

It is not the neurons themselves, but the the glial cells that keep those very large and (potentially) active neurons healthy. Presumably the glial cells must partially shut down in order to physically shrink, thus the neurons must notch down their activity as well.

Locke1689• 13 years ago

Same old story, primitive stop-the-world GC ;)

fsckin• 13 years ago

Have you tried the new polyphasic garbage collector?

Ygg2• 13 years ago

It is very toxic.

daenz• 13 years ago

Maybe that's the solution...have so much memory that you only need to GC once every 24 hours...for 8 hours :)

applecore• 13 years ago

That's pretty much how trading systems work.

sillysaurus25• 13 years ago

A "toxin" is something which is toxic to a system. But our knowledge of the brain is so primitive that we can't reasonably claim to know which chemicals are toxic at tiny, long-term dosage levels, unless it leads to death. There is no evidence that it's possible to die directly from sleep deprivation. Therefore this seems a dubious headline.

foobarbazqux3• 13 years ago

If you don't sleep for long enough (about 7 days), you'll start to have visual and auditory hallucinations and also delusional thinking. You'll also experience severely reduced effectiveness of just about every system in your body. You might not die if you don't sleep for a year (say), but you'll probably get permanent brain damage.

sillysaurus25• 13 years ago

The point of science is to never fall back on claims like "you'll probably get permanent brain damage" unless it's known what brain damage you may get, along with bounds on a confidence interval. Otherwise we're just philosophizing.

meowface2• 13 years ago

Many people experience hallucinations if they stay awake for periods longer than 48 or even 36 hours.

aestra2• 13 years ago

In clinical settings people experienced hallucinations with less than 48 hours of sleep deprivation.

http://www.amsciepub.com/doi/abs/10.2466/pms.1989.68.3.787?j...

I have no idea where you get 7 days from, I'm not sure its possible to stay awake for 7 days.

scott_s• 13 years ago

The word "toxin" has become a signal for pseudoscientific medicine, so I also furrowed my brow at that. But the original use of the word is much more clear in context. From the abstract which tokenadult kindly linked to:

Thus, the restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system.

Also, regarding the dangers of sleep deprivation, the first paragraph of the paper are relevant (http://www.sciencemag.org/content/342/6156/373.full):

Sleep deprivation reduces learning, impairs performance in cognitive tests, prolongs reaction time, and is a common cause of seizures (3, 4). In the most extreme case, continuous sleep deprivation kills rodents and flies within a period of days to weeks (5, 6). In humans, fatal familial or sporadic insomnia is a progressively worsening state of sleeplessness that leads to dementia and death within months or years (7).

Reference 7 is http://www.thelancet.com/journals/laneur/article/PIIS1474-44..., but I found the Wikipedia article more consumable for someone who is not up on medical research: http://en.wikipedia.org/wiki/Fatal_familial_insomnia

sillysaurus25• 13 years ago

Direct link to reference 7, "Familial and sporadic fatal insomnia": http://a.pomf.se/7Uu7.pdf

From the paper, "Phenotypic variability is another issue. In some patients, insomnia, one of the cardinal symptoms, was not reported."

The other half of that sentence is obviously "... but Dementia and death still occurred."

Therefore, this research demonstrates that fatal familial insomnia results in Dementia and death, but with insomnia as a secondary effect. The insomnia is a symptom, not the cause.

I'm only trying to show how tricky it is to base an argument on scientific research. There are all sorts of corner cases and gotchas. In this case, the fact that insomnia is unrelated to the Dementia and death is buried on page 8 of a 10-page article, embedded in a gigantic paragraph. A rather important point for such little treatment by the article!

rusew• 13 years ago

Rats die "within a matter of weeks" if they do not sleep: http://www.sciencedirect.com/science/article/pii/01664328950...

sillysaurus25• 13 years ago

Curses, you've made me break my "No HN on my work computer" anti-procrastination method. At least it's been only 15 minutes though.

Direct link to the research: http://www.gwern.net/docs/algernon/1995-rechtschaffen.pdf

The paper is titled "Sleep deprivation in the rat by the disk-over-water method." As the name implies, rats are suspended on a disk over water. They can't fall asleep without starting to drown. Thus they are kept awake.

The paper begins with, "Because short-term sleep deprivation (SD) may stimulate only sleep-promoting mechanisms, chronic SD may be required to elicit function-revealing deficits. However, the enforcement of chronic SD requires repeated, intrusive stimulation which can blur the interpretation of effects. Do they result from sleep loss or from the strong stimulation used to enforce SD? To simplify communication, we speak of the 'effects' of SD, but strictly speaking, SD studies are correlational. We apply stimuli to enforce SD and report the relationship between the ensuing sleep loss and changes in performance or physiology. However, the changes and the sleep loss could be independent responses to the stimulation. The interpretation that the changes result from sleep loss hinges on minimizing the contribu- tion of the deprivation-enforcing stimulation, which can be especially difficult when strong stimulation is used to en- force chronic SD."

There are two possibilities. Either rats being repeatedly almost-drowned doesn't contribute to death after 45 days, or it does. The paper goes on to demonstrate the steps they took to minimize the chance that almost-drowning rats resulted in death:

"Hypothermia had been suspected as a proximal cause of death [3,31,34] because all SD rats showed an eventual decline in intraperitoneal temperature (Tip); a decline to more than 1 °C below baseline in otherwise untreated SD rats has been a reliable indicator of impending death within a day or two. However, TSD rats kept warm by exogen- ous heating died nevertheless"

"A second possible cause of death is breakdown of body tissues due to catabolism, secondary to the high metabolic rate in TSD rats [3,14,31]. [...] Evidence against catabolism as a mediator of preterminal effects includes a lack of preterminal serum albumin de- cline in PSD rats [22] and the deaths of all rats in two TSD groups protected against catabolic effects, hypothy- roid rats and high-calorie diet rats. Thus tissue breakdown secondary to catabolism was not a necessary cause of death."

However, this third point is a key conflating factor:

"A third major candidate for proximal cause of death is organ failure secondary to systemic infection, as suggested by bacteremia, which Everson has observed in five of six TSD rats obviously near death [11]. We subsequently confirmed bacteremia in two additional preterminal TSD rats [20]. Very recently, we treated six TSD rats with antibiotic cocktails; five progressed to an apparently ter- minal condition nevertheless and were then killed (after 10-16 days of TSD). Neither heart blood samples, livers, kidneys, nor mesenteric lymph nodes showed aerobic bac- terial or fungal infection. The sixth rat died after 19 days; blood could not be drawn, but the other tissues were har- vested shortly thereafter and were also free of aerobic bacteria and fungi. These results indicate that microbial invasion is not a necessary cause of death in TSD rats."

If you read carefully, they begin by saying "almost-drowning rats eventually results in organ failure." They end with "microbial invasion is not a necessary cause of death."

I think it's possible that almost-drowning rats causes organ failure for reasons other than microbial infection. The fact that the rats progressed to a terminal condition even after antibiotics seems to support this hypothesis. Their organs failed anyway. I wonder if dunking them in water for a month had something to do with it, and not the sleep deprivation?

The paper seems to tiptoe around this point.

azakai• 13 years ago

A "toxin" is something which is toxic to a system. But our knowledge of the brain is so primitive that we can't reasonably claim to know which chemicals are toxic at tiny, long-term dosage levels, unless it leads to death.

If it leads to harm or death of individual neurons, we have lots of knowledge about such things. For example, we know that glutamate is toxic in large doses to neurons,

http://en.wikipedia.org/wiki/Excitotoxicity

rosser• 13 years ago

There is no evidence that it's possible to die directly from sleep deprivation.

Perhaps not directly, as the actual cause of death in FFI is unknown, but:

https://en.wikipedia.org/wiki/Fatal_familial_insomnia

sillysaurus25• 13 years ago

Actually, the insomnia isn't the cause of death. FFI is just a bad name for the disease. https://news.ycombinator.com/item?id=6568961

greenyoda• 13 years ago

Wikipedia has a decent article on the glymphatic system, which clears waste products from the brain:

https://en.wikipedia.org/wiki/Glymphatic_system

The brain and spinal cord have no lymphatic circulation, which handles waste removal for the rest of the body.

batgaijin• 13 years ago

I always wondered about how split-brain theory would work into this...

I mean there are stories of people with half their brain removed who are fully functional (I think? I can't find a source atm).

I wonder what would happen if half your brain could be on/off and switch?

Also you'd think that any mutation optimizing for time awake would have decimated the other creatures? I don't get how evolution has conquered everything but sleep.

whateverfor• 13 years ago

There are actually animals that sleep half a brain at once: all the marine mammals. A dolphin can't just fall asleep underwater (it will drown), so it sleeps half at a time.

There are creatures that sleep very little (Giraffes, etc.) But there's large benefits to sleep, and for most animals it's worth the cost, especially since you don't want to burn piles of calories during non-peak hunting/foraging hours anyway.

soneca• 13 years ago

On that post about a bird that fly for 6 months in a row there were a discussion about the sleep in animals. Some of them are able to sleep alternating one half sleeping and the other aware of the environment. And there is speculation if that bird could sleep while flying.

I think half brain awake is not enough to have a fully functional life. I also heard about people losing part of their brain and adapting to deal with it. But that doesn't mean a brain doesn't need that part. It is like the fallacy of using only 10% of the brain. The brain is very well used and optmized for performance, if you lose part of it, it would adapt to compensate what is missing, but it will not be optimized anymore.

Disclosure: just guessing here, I have no scientific knowledge or background at all to support these claims of mine.

dkersten• 13 years ago

In the case of the bird, it may not need fully optimized brain to fly. So it might be acceptable to have reduced brain performance as a tradeoff for longer awakeness, especially if you could recharge under reduced performance and then go back to fully awake (and rested).

emiliobumachar• 13 years ago

you'd think that any mutation optimizing for time awake would have decimated the other creatures?

Maybe the specialization into day/night has something to do with it. The decimator would need to stand their ground against nocturnal creatures at night and diurnal creatues at day.

drited2• 13 years ago

The people who have had half their brains removed (Hemispherectomy) and are functional had it removed when they were very young and the other side wired to adapt. Depending on age of operation, there may be more or less significant impairments for life.

For humans with 2 healthy hemispheres, as far as I'm aware better imaging is revealing that split brain theory is only partially correct for many of the processes that were formerly thought to happen in one half only. Recent imaging has shown that the other half is still involved, albeit in a less widespread fashion.

dbecker• 13 years ago

"The brain only has limited energy at its disposal and it appears that it must choose between two different functional states - awake and aware or asleep and cleaning up,"

Sure sounds like part of the wake-sleep algorithm, which is impressive given that the wake-sleep algorithm was named in the mid-90s.

samstave• 13 years ago

What about meditation? Does mediation allow for "asleep" like cleanup activities whilst in the "awake" state?

pstuart• 13 years ago

That might be more akin to reducing bus contention.

dsrguru• 13 years ago

"The brain ... must choose between two different functional states - awake and aware or asleep and cleaning up"

As any lucid dreamer can tell you, there's also a third option--asleep and aware.

nikatwork4• 13 years ago

Not to mention hypnagogic / sleep paralysis - mind awake, body asleep.

Miyamoto• 13 years ago

Awesome. One very (very very) small step closer to creating a pill to help the flushing process so we may sleep less, or not at all.

jessriedel2• 13 years ago

Seems unlikely. Essentially all animals with a brain sleep, even flies. You'd need to find a pill that could do something that not one animal was able to evolve to do over hundreds of millions of years. Something that was extremely calorie intensive is all I can imagine.

wtvanhest• 13 years ago

I appreciate your logic, but there is a wide variety of needed levels of sleep among different animals, and even among different individual humans which tells me that some are more efficient than others at sleeping (maybe clearing toxins?).

As efficient as evolution is, the ability not to sleep as much may not be a huge determinant in reproduction. Just 100 years ago, people worked all day, then relaxed and slept. There was little to no demand for not sleeping at all from a survival standpoint.

The main reason people want to stay awake all night now is to work more and advance their careers. You don't need that for survival.

Further, Pharma companies have done some amazing things. While I agree that it is unlikely soon, I am confident that if humans are around in 200 years, it becomes much, much more likely.

nikatwork4• 13 years ago

a pill to help the flushing process

I'm afraid this will require nanobots.

jotm2• 13 years ago

I'd be happy with a pill that speeds up the sleep/recovery process - it seems easier to achieve and it wouldn't go against millions of years of evolution...

jimgardener• 13 years ago

It would be nice if my computer did all scan/cleanup defrag ops after I shut it down and go to sleep

_-_-_-• 13 years ago

When I hear "toxins", I think of a developer on a project I helped manage. He was having health problems so he had to take a 1-1.5 month sabbatical to India to be cleansed of toxins. If I remember correctly the end result was that he quit.

While I do believe there that the body cleanses itself from toxins, and I can't say for certain whether the developer that left us got his toxins cleansed or not, this article and study smells of B.S.

The second tip off is the quoted doctor's name: Dr. Nedergaard

Scientists with Dutch/Scandinavian names always seem to produce the most crap science on average in my experience. I have no idea why, but I've noticed it. Especially when it comes to the "positive affects" of pot. I know that is an over-generalization, but someone should do a study on that to see if it's true. Preferably one without as many A's in his/her last name.

anotheraccount7• 13 years ago

Well the trophy for most BS per capita definitely goes to the Chinese.Unfortunately If I see a chinese name on an IEEE article and it's not from a reputable university, I skip it.

As for clearing out toxins. It's been known for years that sleep clears free radicals from the brain. That's why very long term sleep deprivation can led to brain damage, and why if you take modafinil you aren't shielded from the physiological adverse effects of sleep deprivations (though mentally you'll be fine).

giardini• 13 years ago

Any implications for napping?

brickcap• 13 years ago

Fascinating. An average 60 year old man sleeps for 20 years (considering a normal 8 hr a day sleep) that is 1/3 of his life. A polar bear and some other hibernating animals sleep for half of their lives. Amazingly polar bear is cognizant enough to feed her baby while she is sleeping.

Sleep also lowers the heart beat. It is generally accepted that all mammals have the same life span in number of hear beats. An elephant lives longer than a mouse because it's heart beats slower. Could that mean that people who live longer generally sleep more.

Whales are known to live for a long time. Wonder how much they sleep.

joshuahedlund• 13 years ago

It is generally accepted that all mammals have the same life span in number of heart beats.

Please note that while there is some correlation it may not be strict enough to suggest that lowering your own heart rate will help you live longer.

http://skeptics.stackexchange.com/questions/5701/does-every-...

drewcrawford2• 13 years ago

This appears to have an interesting implication for FFI [1], a mysterious genetic disease that causes complete insomnia in adults and results in death. The final stage of FFI is dementia.

It turns out that the β-amyloids that are cleared during sleep according to this paper, are associated with certain types of dementia in the general population [2].

It also turns out that certain sleep disorders are dementia predictor [3].

This is just a laymen's speculation, but this is suggestive that dementia may be a type of sleep disorder, that it could be caused by some interruption in the process demonstrated in this paper.

And this is a stretch, but it is known that FFI is caused by a malformed prion protein, which is a protein that is deeply involved in various neuron-related functions. It seems possible that this protein is involved in the cleansing process in some way. If so, that would be a HUGE deal, because abnormal prion proteins are associated with a huge variety of neurodegenerative diseases.

Basically, I have high hopes for future research.

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

[2] http://www.ncbi.nlm.nih.gov/pubmed/17502554

[3] http://www.medscape.com/viewarticle/781136

drited2• 13 years ago

To expand on the dementia issue, poor lighting can lead to disturbances in circadian rhythm and issues with sleep. Fixing this may help with dementia. Further research needed in the area.

Sources: http://www.webmd.com/alzheimers/news/20080610/bright-light-i...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553247/

foxhill• 13 years ago

is your third source accessible from anywhere that doesn't require an account? i'd like to read it.

drewcrawford2• 13 years ago

Paste the URL into Google. It seems that if your referrer is Google, no paywall for you.

srd• 13 years ago

Is it known if there are ways to support the cleanup process?

I ask because due to allergies I have constant sinus congestions and as a result a very light sleep. On average I wake up (to the point where I'm consciously aware that I'm awake) 2 to 4 times per night, persumably due to lack of oxygen.

I'm noticing memory issues; and while the process may not be reversable, I would like to halt it or at least slow it down as much as possible.

dbbolton• 13 years ago

My dad and I are in a similar situation to you- terrible nasal congestion constantly interfering with sleep.

The quick and dirty solution is decongestants. However, vasoconstrictors (pseudoephedrine, oxymetazoline, phenylepherine, etc.) often have a "rebound effect", i.e. when they wear off you find you're actually more congested than you were before you took the drug. In this sense they can be quite addictive. I try not to use any unless it's absolutely necessary, and only once every few days at that.

One thing that helps a little bit is Breathe Right nasal strips. They will often open up the nasal passages enough that I no longer have to struggle to breathe through my nose. If I'm only slightly congested, I use these. I don't know if the increased air flow would be enough to keep you asleep or not, but it's probably worth a try.

For the most part, I have pretty much adapted to function on a few hours' worth of sleep. I can go on a three hour nap twice a day for an indefinite length of time. I don't know if that is enough rest to fully clean up the brain, but I don't feel crappy all the time so I suppose it's good enough. It definitely works better for me than sleeping for 6 hours once a day. I typically sleep in on the weekends, but I recently saw an article claiming that isn't enough to erase slept debt accumulated during the week.

aestra2• 13 years ago

Have you seen a doctor about this?

I know they have CPAP machines which have a heated humidifier, which I presume will keep your congestion under control over the course of the night and your airways open.

I'm no doctor, so go talk to yours and go see a sleep specialists to see why you are awaking in the middle of the night.

lee• 13 years ago

I have sleep apnea and use a CPAP machine nightly. My CPAP device comes with a humidifier chamber to keep the humidity of the air I breathe in high.

One of the side-effects of using a CPAP machine is that sinus congestion never bothers me as long as I have the device on. It provides enough pressure that my sinus are forced to remain open when turned.

So maybe look into using a CPAP machine to help you out.

hkon• 13 years ago

Does it flush the toxins if you take sleeping pills?

willstepp• 13 years ago

Why does everyone in this thread want to get rid of sleep? I like sleeping, and dreaming. 24-7 consciousness in the name of increased productivity sounds like a nightmare, no pun intended.

Technophobe• 13 years ago

How can you enjoy something you're not conscious of? What you likely enjoy is the 5-30 minutes as you're falling asleep, and the 5-60 minutes as you're waking up.

If we could get the actual sleeping time to 1 minute, but keep the rest the same, surely that would be strictly better in terms of human utility.

TaiChiChaiTea• 13 years ago

As someone in their early 20s with a sleep disorder this freaks me out!

Sleep Flushes Toxins from the Brain

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