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Brains Sweep Themselves Clean of Toxins During Sleep (2013)

420 points| phatboyslim | 9 years ago |npr.org

167 comments

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bitexploder|9 years ago

The actual research is quite interesting. Sleep disorders themselves are fascinating. There is evidence that TBI (traumatic brain injury) can cause lasting sleep cycle disruption. Perhaps sleep disruption and TBI is a much bigger factor in the lasting impact of TBI than previously thought.

(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3482689/).

Article review: This is pretty good science reporting, actually providing a link to the study being referenced. My one nit is the use of the word "Toxins". That is a trigger word for me that immediately makes me suspicious of the reporting. Scientific papers about the human body very rarely if ever use the word "Toxins" preferring precise terminology such as "brain waste products" or just keeping to the chemical names at hand. "Toxins" is one of those normative layman words that gets used to sweep up all sorts of ill-conceived explanations and pseudo-science.

pnathan|9 years ago

Yes, "toxic" and "toxins" are incredibly vague. I loathe the use of those words, as they are both scary and nearly meaningless.

mabbo|9 years ago

> The process is important because what's getting washed away during sleep are waste proteins that are toxic to brain cells, Nedergaard says.

Evolution found a nice little optimum in sleep that works pretty well- use less energy during a time of the day that isn't a very efficient time to be awake while also cleaning out the brain.

This could be interesting for future research. Could we find chemical means to remove those waste proteins?

zip1234|9 years ago

Or maybe some sort of mechanical pumping system? If it takes too much energy away from the brain to both remain awake and clear those proteins, a mechanical pump that is powered externally could solve that energy problem. (I'm only half joking--we already have mechanical means of replacing other biological functions such as a dialysis machine).

bryondowd|9 years ago

There's an interesting concept. I wonder what the trade-off would be. How much efficiency would it cost to clean the brain continually rather than in a dedicated sleep cycle? Would it even be possible to process these toxins while maintaining consciousness? I'm sure there could be huge benefits for many modern lifestyles to trade heavily on reaction speed and/or lightly on IQ for 50% more waking hours. Or even 25% more waking hours, if you just cut the need for sleep in half, over the long term.

Tharkun|9 years ago

The blood/brain barrier makes it difficult to deliver chemical means to the brain.

Puts|9 years ago

Maybe looking for the reason we sleep is the wrong way to look at it? What if being asleep is the default state for any organism?

Sleeping require much less energy. The only reason to be awake is to eat and reproduce. For any animal there is probably an optimal ratio between sleep and hunt/reproduction where sleep is the most favorable.

smallgovt|9 years ago

This strikes me as the type of comment that sounds artificially 'deep' but has no constructive or logical basis. What does 'default state' even mean in this context? The fact is we naturally sleep sometimes and we're awake at other times. If you're suggesting there's no reason for sleep other than conserving energy, that's patently false.

The (assumed) primary motive here is to find a way to sleep less. We already have ways to force wakefulness. We now need to find ways to mitigate negative side effects hence the research on various health functions sleep contributes towards.

dbenhur|9 years ago

My cats figured this out quite a while ago.

JimboOmega|9 years ago

But sleeping makes you much more vulnerable to predation, and really doesn't save much more energy vs. quiet/restful wakefulness.

Just think of how disoriented you are when something wakes you up in the middle of night - that's a definite biological cost if that thing is something threatening to you.

And of course, never mind creatures that have gone as far as the 50/50 brain adaptation (IE Dolphins), they simply have to be at least partially awake all the time.

jwilliams|9 years ago

A related and quite recent piece of research - Stimulating toxin cleanup via brain stimulation using pulsed light. Has been used to treat Alzheimer symptoms in mice models. Last I heard was being fast-tracked to humans.

http://news.mit.edu/2016/visual-stimulation-treatment-alzhei...

"This treatment appears to work by inducing brain waves known as gamma oscillations, which the researchers discovered help the brain suppress beta amyloid production and invigorate cells responsible for destroying the plaques."

afarrell|9 years ago

My alma mater has a saying: "sleep is for the weak". If you go to a university with that slogan, here is one more reason why it is foolish.

If you want to learn effectively and work efficiently, take care of your body and take care of your brain.

piannucci|9 years ago

Hey, my alma mater has that slogan too... oh, hi, afarrell.

cbsmith|9 years ago

I always believed that line is intended to be sarcastic.

vkat|9 years ago

Makes me think sweeping is analogous to a halt the world garbage collector.

lmkg|9 years ago

There's already research that being sleep-deprived has similar cognitive effects to being drunk, especially with regards to driving safety. This new result implies that may be more than a coincidence, as the biological underpinnings may be similar.

Overtonwindow|9 years ago

Random thought: Could dreams be a result of the processing of toxins? In the same way some "toxins" cause us to hallucinate etc. so too could these toxins, as a side affect of processing?

clavalle|9 years ago

>The team discovered that this increased flow was possible in part because when mice went to sleep, their brain cells actually shrank, making it easier for fluid to circulate.

It could be that the brain needs to fire up for short periods in order to help pump the increased fluid out to prepare for another rinse.

e40|9 years ago

I read somewhere in the last 10 years that dreams were practice for real life situations. After hearing that, when I awake in the middle of a dream, I always test that hypothesis, and sure enough, sometimes is quite plausible.

d8421l01vv4r|9 years ago

If dreams only were the result of some cleanup process (i.e. just arbitrary neurons firing), I imagine they would be a lot less coherent and all events would be (stochastically) independent. While dreams usually don't much make a huge lot of sense, they are sometimes quite realistic and "past" events seem to influence "later" events.

Yabood|9 years ago

I learned about this from the Learning how to learn class on Coursera. Can't recommend it enough. https://www.coursera.org/learn/learning-how-to-learn

akprasad|9 years ago

I went through the course on your recommendation. Thanks, it was great!

Apparently much of it based on Oakley's book A Mind For Numbers, which I'll try to read soon. Much of the content also reminded me of Josh Waitzkin's The Art of Learning. A related thread elsewhere on HN [1] also suggests Make It Stick by Peter Brown.

[1]: https://news.ycombinator.com/item?id=8815148

joering2|9 years ago

It always amazes me to read articles like this. How come I don't need more than 3 hours of sleep a day and its been like that for over 15 years now?

I sleep "late hours". I go sleep around 8am and wake up around noon. I don't eat breakfast just coffee. I work most of the day on different projects, eat quite large dinner at 8pm, then every day go for 45 min to the gym, around 10pm and then 20 min walk. After that its about midnight and I start working. I don't get tired until 5am but then 2 glasses of water "wake me up". By 8am I'm in bed truly tired.

I been running this schedule for 15 years now, no symptoms of nothing. I don't smoke and don't drink btw. I barely watch TV (never found anything interesting; I take breaks on my PC watching some travel-related documentaries)

Edit: perhaps once a month I feel truly tired and usually on the weekend, I tend to sleep about 8-10 hours. But that doesn't happen often.

colmvp|9 years ago

I remember my friend mentioned to me she might have a mutation in the DEC2 gene (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2884988/) because she usually goes to bed around 2 am and wakes up at 6-7 am, and has been doing it throughout her life. And she says she's fine and like you doesn't feel tired if she only gets 4-5 hours of sleep.

Interestingly, if she gets the standard number of hours of rest (say, 7-8), she gets really groggy and it totally disrupts her ability to function throughout the day!

Jach|9 years ago

Back when I was trying to make the uberman (and eventually the everyman) sleep schedules work for me, I ran across a person like you, it made me incredibly jealous. He seemed to think it was that his brain only went into REM mode for some reason. As the other comment mentioned maybe it's just a simple gene mutation, if so perhaps CRISPR can replicate the effect... Lots of stuff if you google "Short sleepers".

akvadrako|9 years ago

I hope you use this incredible advantage to do something especially unique for society.

It sounds kind of like an evolutionary advantage. Sleep is probably for multiple uses, but I think most could all be handled in other fashions.

The exception is conservation of energy. Yet, that is no longer relevant in the upper part of society.

gh1|9 years ago

Wow that sounds amazing. Did you see anyone (like a doctor or a researcher) and ask for an explanation of how you can do this?

bjornsing|9 years ago

I'd be very surprised if it turns out that there's not a major "computational" element to sleep. Sure, it may be difficult to circulate fluid through a waken beings brain, but I think evolution could have managed. If the "computational resource" is needed for something else though (like running backprop over your neural networks or something :P)... That to me is the only reasonable explanation for the huge evolutionary cost most creatures pay for sleep.

wahern|9 years ago

What's the huge cost? Most land reptiles and mammals spend most of their time idle anyhow, including humans. In many cases sleep is arguably preferable as the animal is less likely to get itself eaten. If you're not foraging or reproducing, your best bet is to hide and stay still. Because animals, especially land animals, tend to be specialized for particular parts of the day or for other scenarios which preclude 24/7 activity, there's not much that can be done in that idle time. Except improve neurological function, apparently.

Animals that need to be constantly in motion have other adaptations.

For modern humans the cost can be immense according to our cultural calculus. I'm not sure it's an evolutionary cost. Only time will tell whether those burning the midnight oil have better reproductive success.

nkrisc|9 years ago

But evolution doesn't "manage" anything. Evolution often plateaus at "good enough." I think this is the risk in the computer metaphor for the brain. Computers have designers that try to optimize them, brains do not.

slmrnz|9 years ago

Reminds me of the good old days of defragging a Windows hard drive :)

ZanyProgrammer|9 years ago

It's interesting that in almost every sleep related article I've read on HN, the overwhelming majority of people who respond about their personal life say that they hate getting up 'early'-for various definitions of early. Surely there are programmers who like getting up early?

rootusrootus|9 years ago

I like getting up around 5:30 or so. Puts me outside the heaviest traffic times and gives me a few hours in the morning of uninterrupted time to mind meld with the computer. And then I get to leave 'early' in the afternoon and enjoy my free time and plentiful daylight.

seizethecheese|9 years ago

Perhaps they aren't posting on message boards during the workday.

cgag|9 years ago

I love being up early but find maintaining an early schedule extremely difficult.

nightbrawler|9 years ago

When I was younger I preferred staying up late and working and it allowed me to get a lot done. As I've gotten older and now have a family, things have flipped and now I much prefer to start my work day early, usually around 6am. This gives me more family time in the afternoon/evenings.

amerkhalid|9 years ago

There a lot of programmers in my company who are in super early and leave by 2-3pm. But I think most of them do it out of necessity because either they have kids or they have long commutes.

tigershark|9 years ago

If I wake up before 8 for work I feel physically tired. In my current job I'm waking up at 7.30 everyday and I feel that I lost 10-20% of productivity. And it is not strictly correlated with lack of sleep because now I'm sleeping at 10.30-11.30 pm. I can do my best work when I have no mandatory early show in the office and I can arrive whenever I want between 9 to 10, ideally after a nice 30 minutes walk to wake up properly.

Klockan|9 years ago

I like getting up early since everyone else likes getting in late and leaving late. For example if I arrive at 6 and they at 10 I will get 4 undisturbed hours of work. To get the same amount on the other end I would have to arrive at 3 in the evening.

tonyedgecombe|9 years ago

I'm an early riser, I do the majority of my work in the mornings.

shocks|9 years ago

I like getting up early, where early is defined as 6am to 6:30am.

scandox|9 years ago

IIRC the story Manhole 69 by JG Ballard references a requirement to divert neurotoxins in men whose sleep centres were disconnected/cauterised.

Ballard I presumed was just speculating. But based on his relatively high level of scientific knowledge I imagined it was rooted in some sort of real world science.

That story was written in the 1960s...so has the state of research on this remained slow or was Ballard just making a lucky guess?

rl3|9 years ago

Title should be updated to reflect 2013.

djsumdog|9 years ago

Yes, I remember seeing this on here several months ago. Still good for all the people who may have missed it.

Mz|9 years ago

Any sufficiently advanced technology is indistinguishable from magic.

s/technology/science

https://en.wikipedia.org/wiki/Clarke%27s_three_laws

At some point, people on HN will get over their fear of words like "toxins" and embrace the Tao Te Woo as the advanced science it is.

gh1|9 years ago

I have heard of at least three believable theories of why we sleep.

- To turn short term memory into long term memory, to consolidate long term memory, and prepare the brain to learn new things.

- To clean the brain of harmful waste products (which is what this article says. By the way, it is old and from 2013).

- An evolutionary artifact of energy conservation in resource-low ecosystems.

Are there some other theories too?

gdubs|9 years ago

I'm currently reading Arianna Huffington's "The Sleep Revolution". If you're interested in more stuff like this, it's pretty good. It's definitely made me more mindful of winding down and night and getting plenty of sleep.

One thing in particular that stood out is the rise in cortisol associated with lack-of-sleep, and cortisol's relationship to gaining fat; having hit a couple of rocky weeks sleep due to young kids at home, this was particularly relevant to me.

I now rank sleep as pinnacle in terms of health / fitness training, mental well-being, creativity, etc.

djsumdog|9 years ago

There have been two Vox articles about people who are biologically late sleepers are often viewed as "lazy." It's sad considering the current state of sleep deprivation throughout the western world.

I hate being up early for work. I am 9am scrum since our team is spread out over the planet and it's truly painful. The right attitude is not "you should get to bed at a reasonable time," since I often get bursts of productivity between 11pm and 4am. I'm probably the most productive in that window.

Choosing jobs and career paths based on your sleeping pattern (and overall heath) should be encourage more over money or benefits or retirement or all of those other bullshit traps:

http://khanism.org/perspective/trapped-in-the-cubical/

ramshanker|9 years ago

Wild analogy.... Inference machines cleanup the neutral model itself when put to relax. Wait, are there any Neural Nets out there, which produce toxic "weights" to be discarded later, If not than we are far from copying the real glucose based neural networks. /Imagination

jacquesm|9 years ago

> Wait, are there any Neural Nets out there, which produce toxic "weights" to be discarded later

That's what 'dropout' is for ;)

m3kw9|9 years ago

I think rest in human term is different than machines. Also, that is just a cleanup mode, machines can induce that with or without "rest"

kgdinesh|9 years ago

so sleeps are basically GC pauses.

eof|9 years ago

I bet meditation, or a state that can be brought on by meditation, has this same effect.

empath75|9 years ago

This should worry all the people taking adderall and modafinil to be more productive.

kristofferR|9 years ago

There's a massive difference between using stimulants to be more productive and using stimulants to skip sleep.

deathhand|9 years ago

Additionally-when ingesting any number of substances that changes cognition my personal antecedent to add is that 'I just don't feel right' unless I nap.

This is true for all things one would imbibe to 'escape reality'.

mrleinad|9 years ago

I take modafinil on a daily basis each morning, and have a regular sleep pattern of 7-8 hours a night.

It even helps with going to sleep earlier, because I feel depleted by 10 PM, so there's less incentive for me to stay up and waste time that I could use resting for the next day.

prodtorok|9 years ago

Why?

lucaspiller|9 years ago

This article is from 2013. Has there been any further research published since then?

convales|9 years ago

www.ted.com/talks/jeff_iliff_one_more_reason_to_get_a_good_night_s_sleep