The brain makes a lot of waste. Now scientists think they know where it goes

https://www.npr.org/sections/shots-health-news/2024/06/26/g-s1-6177/brain-waste-removal-system-amyloid-alzheimer-toxins

by robg • 2 years ago

274 175 2 years ago

xnx2• 2 years ago

It may sound a little woo woo, but I definitely feels this. After duration of difficult mental work (often difficult reading) I can feel my ability to focus slipping and eyes getting heavy. If I can successfully take a short deep nap (sometimes less than 15 minutes) all that is flushed away and I can focus again. Weird analogy, but a the relief is similar to emptying a full bladder. Related, not napping in these circumstances seems like it would be very unhealthy and damaging.

mozman• 2 years ago

I love to nap after a brain draining moment. I’m revitalized and ready to go. One of the major WFH benefits.

adversaryIdiot• 2 years ago

yep, i cant stand in office work

coffeebeqn• 2 years ago

Yep because at the office it will be multiple hours of fighting having to sleep and literally getting nothing done while trying to not appear totally unconscious

crocowhile2• 2 years ago

yes, we've known for two centuries that a couple of hours of extra sleep can help us undo the effects of days and days of sleep deprivation. This is one of the strongest argument against this brain clearance non-sense. If we can get this done in 15 minutes, why sleep 8 hours a day?

janalsncm• 2 years ago

It would be an amazing gift to be able to sleep even only half the time every day.

That said, I have had the unsettling thought that the brain is never really “off” during your lifetime. With computers you can restart them, but your brain keeps going, even when you’re sleeping. So I think we should be nice to our brains.

crazygringo2• 2 years ago

Where are you getting 15 minutes from?

That might be enough to recharge you to a normal level after something particularly taxing.

It's not enough to restore you completely, and certainly not after an entire day's worth of activity.

And there's so much more to sleep that you're missing, like consolidating memories, muscular coordination habits and patterns, etc.

xarope• 2 years ago

solo sailors (amongst others) do this; 30-90mins of sleep each time, but they cat nap all the time, not just once a day.

However, research shows that long term learning etc, as well as critical decision making, are impaired.

My anecdata of 1; I prefer 6-7 hours of sleep, but during some expeditions, I'd be lucky to get 2-3 hours before a summit attempt of 12-18 hours (leave at 1-2am, return to high camp by 3-4pm, pack up and head down to a lower level for safety). For safety, I make sure to practice all the skills required (rope, carabiner and knot handling) so these are "routine", and not require more cognitive effort to "figure out".

A funny story during an expedition: a friend couldn't lift his foot whilst we were all preparing for some ice traverse - it was stuck for some reason, we all stood around wondering why, and we finally realised I was standing on one of his crampon straps. I swear it took us 10mins to figure this out, a result of sleep deprivation, high elevation, being swathed in layers of clothing, and general fatigue.

JKCalhoun3• 2 years ago

If it were possible, not harmful, I imagine we would already be doing it. Ain't evolution grand?

Qem2• 2 years ago

Perhaps decrease of waste with sleep is exponential, not linear. After days of sleep deprivation, waste concentration is very high, so initial clearance rate is very high as well. As is clears, concentration decrease, so concentration rate also decreases.

candiddevmike• 2 years ago

I wonder if they will study the waste buildup of various polyphasic sleep cycles like Everyman.

therobots92711• 2 years ago

I wish I could take naps like that. I’m lucky that I don’t have trouble falling asleep at night but once the sun is up it’s like my brain just refuses to shut off. Once every week or two I’m able to pull off a nap in the late mornings.

srcreigh3• 2 years ago

It’s not necessary to actually fall asleep. Just set a timer and relax.

For me it’s only a semi-conscious pre sleep state, but it helps significantly.

Do this if you get tired while driving too. It’s a life saving practice!

(And no, driving tired isn’t always due to bad nights sleep. Glucose spikes can be dangerous even if you sleep well at night.)

quartesixte• 2 years ago

You’re not far off the mark. Many jobs/skills that require intense mental concentration report practitioners needing a rest period or having an upper limit to performance.

A notable example I remember are the United Nations’ live interpreters. They can only interpret a live conversation for only about 45 minutes before they have to switch off with a new interpreter because the error rate just exponentially goes up due to mental fatigue.

SoftTalker• 2 years ago

My dad would say he wished the day was about 30 hours. He liked to work long stretches, 10-12 hours, and then unwind for a few hours and sleep for 12 hours. Unfortunately just didn't work well with the real world.

JKCalhoun3• 2 years ago

Earth, anyway.

JKCalhoun3• 2 years ago

Not weird to me — I feel it too. And I always described it as feeling like a wave of ... release, passing over my mind. It feels wonderful and I wake with a clarity as though a weight were lifted from my mind.

Grimblewald3• 2 years ago

It might also just be energy stores filling up again. Its like running, if you take a short break you can often get going at a good pace again, not just because you get your breath back but also energy resverse replensih

akira2501• 2 years ago

Which makes the "false doctor" voice of my ego say "hmm.. could be pre-diabetes."

alan-hn3• 2 years ago

A little confusing, I thought we've known about the glymphatic system for a while now

crazygringo2• 2 years ago

What's confusing?

The article is literally about how we've known about the glymphatic system but not what its mechanisms actually are, and this is precisely about now figuring out the mechanisms.

alan-hn3• 2 years ago

The title. Now we know where it goes, but we knew that already. This article is from this month

pedalpete7• 2 years ago

Surprisingly, the glymphatic system was only discovered a decade ago. The new part is this 40hz light and sound, which has only be done in mice so far.

alan-hn3• 2 years ago

A decade is a very long time in a field as young as neuroscience

jawon• 2 years ago

"The team used mice that develop a form of Alzheimer's. They exposed these mice to bursts of sound and light that occurred 40 times a second.

The stimulation induced brain waves in the animals that occurred at the same, slow frequency.

Tests showed that the waves increased the flow of clean cerebrospinal fluid into the brain and the flow of dirty fluid out of the brain. They also showed that the fluid was carrying amyloid, the substance that builds up in the brains of Alzheimer's patients."

Does this mean we might be able to use something like TMS instead of sleeping?

And could a failure or reduced functioning in this system explain those people "allergic" to electromagnetic radiation?

treprinum4• 2 years ago

https://www.youtube.com/watch?v=UVne_84qZkA

h0p32• 2 years ago

That noise gave me cancer. Thank you.

tsol• 2 years ago

Cleaning the brain is one function that is fulfilled during sleep, but it isn't the only function. Even if you can artificially induce this you would probably need to sleep for other things such as physical recovery(which intensifies during sleep). There may be a chance that it helps lessen the need for sleep or maybe even remove some of the deleterious effects of sleep deprivation

AuryGlenz2• 2 years ago

I volunteer to try it out. I have idiopathic hypersomnia and if I get even a few minutes short of what I’m supposed to it (seems to) hit me like when most people get a few hours short.

Seriously. Anyone in HN know how I could replicate this?

ekianjo• 2 years ago

mice models are notoriously known for being bad to predict anything related to the actual disease pathways

SV_BubbleTime3• 2 years ago

“Humanized mice”… yea, still mice though.

I’m kind of not joking that I think asking for medical study volunteers from prison populations in exchange for time served would put us way ahead.

Or instead of the death penalty, we try some things out that maybe might not work.

We would have cured for colds, cancers, and hair loss in a few years of human testing.

sandwitches• 2 years ago

Here's a good rule of thumb: any time you try to undo a billion years of evolution, there will probably be unintended side effects. Go to bed.

SV_BubbleTime3• 2 years ago

Yea… um, also… I like sleeping. I find it a nice change of pace compared to the rest of my day.

euroderf• 2 years ago

New daily/weekly schedule based on tracking animals to exhaustion:

1) Walk for a day or two, with naps during afternoon heat. 2) Eat absolutely enormous meal. 3) Sleeeep. 4) Repeat.

caeril• 2 years ago

"Go to bed" is useless advice. Some of us are unable to sleep longer than about 5 hours. Room darkening, white noise, complete silence, 8Sleep mattress pad, extended release melatonin, caffeine abstinence, going to bed later, going to bed earlier, nothing works. We just naturally wake up after 5 hours, no matter what, ready to go.

Grimblewald3• 2 years ago

Sleep is about more than waste removal. You cant really learn new things without sleeping on it.

XorNot• 2 years ago

That's making an assumption that the two aren't actually entirely linked phenomena.

spacetimeuser54• 2 years ago

If 40 times a second is 40 Hz, than this frequency is pretty high for a deep sleep (in humans), 40Hz would mean some intense pattern recognition/focused attention.

BigParm• 2 years ago

"Does this mean we might be able to use something like TMS instead of sleeping?"

The trillionaires will greatly benefit from our new 20 hour work days.

j1mmie2• 2 years ago

during sleep, slow electrical waves push the fluid around cells from deep in the brain to its surface.

Is that what dreams are? Electrical waves and fluid knocking on our brain cells?

supple-mints3• 2 years ago

No.

cen4• 2 years ago

Read this book few years back, that dreams are a way of different regions of the brain to defend territory. So the neurons in the visual processing region stop receiving input signal when one sleeps. Those neurons can then be used by neighboring regions for whatever. To prevent that takeover pseudo signals are created to keep them busy. Can't remember the name of the book, but it was a pretty cool theory.

EDIT: found the book - Livewired by David Eagleman

gradientsrneat3• 2 years ago

Dreams occur during REM sleep.

j1mmie2• 2 years ago

This also fits well with the theory that lack of deep sleep increases the risk of alzheimers and dementia:

https://www.medicalnewstoday.com/articles/not-getting-enough...

clumsysmurf• 2 years ago

Just a few weeks ago this appeared somewhere on HN

https://www.sciencealert.com/study-finds-sleep-may-not-flush...

SubiculumCode• 2 years ago

Not an expert in the field, but from what I understand the idea is very contentious with sizeable camps on both sides, especially noticeable if you are talking to an Alzheimers scientist, or a immune system scientist.

ashtami82• 2 years ago

@clumsysmurf, nice catch!

Could it be possible that the coffee lobby is behind this 'counter'-study?, since a relatively simple inference from the OP has catastrophic consequences for the coffee business:

Deep sleep is necessary for the slow electrical waves that clear the brain of waste including amyloid proteins. (Excessive) coffee intake reduces the quality and quantity of deep sleep, thus leading to a build up of waste products including amyloid, resulting in cognitive declines such as Alzheimer's etc. Therefore, coffee intake (indirectly) causes Alzheimer's.

Admitting that last part is suicidal for the coffee business.

gradientsrneat3• 2 years ago

Very interesting article! However, the reduction of clearance rate (30%) is not a lot. It is possible the brain produces even less toxins while asleep. And the article also acknowledges there may be an increase in "bulk flow of fluid." All that said, this study was done on mice, so it's hard to draw conclusions.

bamboozled• 2 years ago

I've read that exercise negates all of this...

Tarsul• 2 years ago

I've found out (the hard way) that chronic lack of sleep leads to not having enough energy for intense workouts... (walking is ok though)

ewgoforth• 2 years ago

In what way? It can make up for a lack of sleep?

pvaldes• 2 years ago

exercise negates all of this...

That would be logical taking in mind this article

hattmall• 2 years ago

So is this similar to the idea behind 40hz binaural beats?

skeledrew8• 2 years ago

40hz is kinda off the scale, and is for very high concentration, so even though it matches off-hand that's a point to consider.

gradientsrneat3• 2 years ago

This study was done on mice, so the equivalent frequency for humans (if it exists) is likely lower.

treprinum4• 2 years ago

No, they used pulses (ta-ta-ta-ta-ta 40 times a second) not continuous waves.

therobots92711• 2 years ago

It’s pretty incredible that by showing the mice a light and music show, they were able to induce drainage of brain waste. That’s really exciting and I would love it if they could invent a hat to wear at night that accelerated the process while sleeping, effectively multiplying your time spent sleeping by some factor. It could be really effective for people with tough work schedules like doctors, truck drivers and pilots.

supple-mints3• 2 years ago

If you haven’t already, try taking melatonin before bed. I found my sleep to decrease in length but I wake more rested.

jdironman• 2 years ago

I feel this will be very subjective of course. The biggest thing I have found I can do for a full rest (not length but quality) is no screens at all after 8pm and no lights except candle light after 930pm, coupled with reading by candle light. Melatonin does help me occasionally but it's hit or miss. Reading instead of watching or listening seems to be the biggest help. I guess different parts of my brain fires during that activity than normal.

justinclift• 2 years ago

Make sure to check if it's legal in your jurisdiction before attempting to go and buy it.

Saying that from personal experience after I returned to Australia from the UK, and popped into a local pharmacist to grab some to try it out. The lady behind the counter and the customer next to her acted like I'd literally asked to buy heroin. (!)

It turns out Melatonin wasn't legal to buy at that time (a few years ago now), though the law has apparently been changed since.

ilaksh• 2 years ago

Vitamin D3 might also help.

therobots92711• 2 years ago

I need to get back into taking that. Good idea!

RamblingCTO3• 2 years ago

Or, you know, fix the issues that prevent you from sleeping instead of messing with hormones. If you really need to sleep, take some GABA. Otherwise, work on it and maybe take magnesium.

Lammy2• 2 years ago

It could be really effective for people with tough work schedules

If such a thing were invented it would effectively become mandatory, because anybody not willing to use it would be out-competed for work by people who were.

GenerocUsername• 2 years ago

Yes, but early adopters would either move up in socioeconomic status, or develop new horrors beyond comprehension

shepherdjerred• 2 years ago

This is entirely dependent on how people value free time vs money. The average person in the developed world would probably take the free time over more money. People already hate working 40 hours.

titanomachy• 2 years ago

I don't know if that's true. Exercise, meditation, adderall, and spaced repetition learning all improve work performance for knowledge workers and those things are far from universally employed.

Qem2• 2 years ago

If such a thing were invented it would effectively become mandatory, because anybody not willing to use it would be out-competed for work by people who were.

I believe this dynamic is already happening to ADHD drugs.

pedalpete7• 2 years ago

We've been working on this for about 4 years now at AffectableSleep.com - not 40hz, and not light. Phase-targeted auditory stimulation which has more than 10 years of research in humans.

therobots92711• 2 years ago

Very cool. I’ll take a look!!

barbazoo• 2 years ago

I wonder what people think of the research this is based on https://www.affectablesleep.com/science

MrDrMcCoy3• 2 years ago

Very interesting. Do you think this will ever turn into a device that regular people can buy? I've been an insomniac my entire life, and would be very interested in trying something in this space.

spacephysics• 2 years ago

Random fun theory. I wonder if there’s any connection to light shows at EDM concerts inducing specific effects

skeledrew8• 2 years ago

There might already be something available in the form of binaural beats. Not a hat, but a pair of earphones and a BB app or audio track...

brcmthrowaway• 2 years ago

I wonder how red light on the brain is mixed in with this

willmadden• 2 years ago

I thought exercise was the key to flushing proteins out of the brain?

dorkwood• 2 years ago

Yeah, I was expecting mention of exercise too.

aamoyg• 2 years ago

I was going to say onto the Internet as a joke.

nakedneuron• 2 years ago

Glad you didn't!

hbarka• 2 years ago

Since it’s a fluid, what about the effect of head angle during sleep?

skeledrew8• 2 years ago

So finding ways to help the brain clean itself — perhaps by inducing those slow electrical waves — might prevent a wide array of disorders.

Even before getting to the end this had me thinking of binaural beats. Back in college there was a beat that I would use whenever I was super tired and had a lot to do, and it'd help me refresh via a quick 20m nap (sometimes the nap itself wasn't even needed; just to let my mind be taken by the beat for the duration). If it's the case that a part of the effect is to trigger a "deep clean" (I've wondered on and off what's really happening), then this just may become a way to reduce said disorders...

jimmaswell• 2 years ago

could you find the exact one?

elcritch• 2 years ago

There are lots of them on YouTube now. I listen to one most nights. Just search for “sleep” and “binaural beats.

skeledrew8• 2 years ago

The beat frequency? Not really; I used an app called Gnaural (on Android, hasn't been updated in years), and just selected the "Power nap" profile. It'll be theta or delta though, maybe a combination.

mrtksn• 2 years ago

IIRC they ware selling tracks that were supposed to make you smart or calm etc. I torrented the most expensive one which the legend said it costs 1000$ and makes you smart, didn't change a thing but maybe because I didn't pay for it :)

soco• 2 years ago

You saved 1k$ and that looks quite smart to me. So... success?

hhjinks• 2 years ago

I remember those vividly. We were on a school trip, and some of the girls heard about it and wanted to try the Speed track (as in the drug). It certainly altered their consciousness, one of them even fainted. We tried to keep it a secret from the teacher, but it eventually got out, and I think all of us on that trip got confronted by the teacher during parent–teacher conferences.

We were all like 14, so we had no idea what Speed actually was like. Seemed almost real for a minute there, but of course it's more akin to hypnosis than actual brain alteration.

skeledrew8• 2 years ago

Binaural beats is a phenomenon though, not a company, so no need to pay for anything ;). Of course there will be those creating tracks or generators with their "special sauce" and charging for it. Kinda like selling shell necklaces so you don't have to gather the shells and make one yourself.

RamblingCTO3• 2 years ago

How would audial waves affect the brain as electrical waves? I don't think that's possible. I'm figuring they'd need to directly take effect in the brain tissue itself to clean it.

phasel0ck• 2 years ago

Potentially via the ear in the same way that a microphone translates sound waves (vibrations in the air) into electrical signals. Just a guess. Seems like there must be signal-flow from from the ear to the brain that involves electricity and the recreation of the signal to be processed by the brain.

mtve• 2 years ago

you may also check out the quite logical and convincing "Visceral Theory of Sleep":

The visceral hypothesis suggests that during sleep, the central nervous system, particularly the cerebral cortex, switches from analyzing exteroceptive information to analyzing signals arriving from interoceptors distributed throughout all the systems of the body

phillias• 2 years ago

This is huge

EADDRINUSE• 2 years ago

Guess this is a similar mechanism to why brainfog is gone afer a powernap? Lets hope that with enough research one can induce it for the people in need some day.

coppsilgold• 2 years ago

I was able to recreate the audio they used.

    sox -b 32 -Dr 96k -n 40hz_1ms_pulse_1hour.flac synth 0.001 sin 10k fade t 0.0005 0 0.0005 pad 0.024 repeat 140000

The goal appears to be to stimulate input neurons 40 times a second in order to drive that frequency as deep and as far into the brain as possible. They succeeded in this objective in mice by combining sound, light and touch (through vibrations).

The hypothesis is that driving neurons in this way aids in the removal of waste in the brain. It would be nice if they are correct.

The brain makes a lot of waste. Now scientists think they know where it goes

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