
Discovering the brain’s nightly “rinse cycle” - rkolberg
https://directorsblog.nih.gov/2020/03/05/discovering-the-brains-nightly-rinse-cycle/
======
tazedsoul
If I could pick one of the things to optimize all of society around, it would
be sleep. I believe that many of society's ills can be traced back to people
being sleep deprived on average. Modern society both ignorantly and through
sheer foolishness undervalues sleep. I understand the emotional motivation for
a statement like, "you can sleep when you're dead," but I do despise this
prevelant sentiment which has become a culutre.

~~~
thisisnico
Our society is so focused on productivity that we forget that the foundation
for improved productivity is sleep, exercise and diet. Mind & Body, one
system.

~~~
anbotero
I enjoy my sleep thoroughly and I sleep 7-8 hours a day. Still, I think it’s a
waste of time, and I don’t mean work productivity, but life. You sleep, wake
up, and surprise, a third of the day has just gone by and you didn’t even
notice.

I recognize the need to sleep, but I personally just wished we could develop a
way to keep going with your day without sleeping. If that were physically
possible, I’d just meditate some few hours daily instead of sleeping 7-8
hours.

~~~
zoomablemind
If you factor in that during sleep your body is actively restoring your
organs, and mind is flushing/filing the info collected during the wake hours.
How many hours needed for that is an intriguing question. But hardly this time
is wasted, unless your sleep is ... restless.

I recently watched an episode of "Nova" on the subject of sleep (Mysteries of
Sleep), very convincing , even to some toddlers fussy about the sleep as usual
:)

~~~
TeMPOraL
Still, it's upkeep. It's necessary, but I wish it wasn't, because it's
expensive.

~~~
anbotero
Exactly my point

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unionemployee
As an airline employee who sometimes faces large shifts in sleep times, I've
become quite worried about brain health. Papers like this and Matthew Walker's
recent popularity seem to have brought more attention to the issue. Last week
I slept from 9pm - 2:30am, 12am - 7am, 7am - 11am, 9pm - 6am, in that order.
The week before I had to wake up at 1am two days in a row. It isn't possible
to function normally on such a schedule and it's horrible for your health, yet
that fact is completely ignored. I'd be considered alarmist and met with a
"suck it up" attitude if I were to take a stand against such things. The FAA
wipes their hands of it by saying that it's "your responsibility" to make sure
you've gotten adequate rest and to call in fatigued if you haven't, but one
would soon lose their job for doing so as often as would truly be required.
Flying an airliner is easy, but we have two pilots because one or both are
often totally exhausted, whether they realize it or not. Operating on "stem
power" is a phrase sometimes used, as in, 'so tired that your higher level
functions are shot and you're operating on brain stem power alone'.

~~~
blaze33
I feel your pain... Reminded me how quite similar it seems to be for hospital
staff: alternating night and day shifts, extra long shifts like 24hr of
continuous work. When asking "but how can you deal with it and know you keep
working properly at all time?", answers consistently seemed to dismiss it
being an issue like "oh, you get used to it..." but I must admit I'm still
having a hard time believing it...

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gentleman11
I was in a car accident once and injured my neck. I got a lot of mental
fatigue afterwards and in particular the angle of my neck can trigger a lot of
tiredness very quickly and reliably. It comes with a swooshing squirting sound
in the back of my head... iirc other people can hear it too when it happens.

I can’t help but wonder if it’s related to this rinse system in some way.
Luckily it has improved a ton over the years but a bent neck still triggers it
and I never found out why

~~~
ehnto
You could have some kind of malformation or inflammation from your injury
causing a build up of cerebral fluid, so when you move it's able to rush past
into the spine and make the funky fluid noises. In perfectly healthy people,
the flow is controlled by a sort of tonsil, and during movement or
laughing/coughing it is able to escape into the spine as well. In people who
have a malformation from birth, it can cause all kinds of physical
developmental issues like lopsided muscle reactions, scoliosis and such. It
also gets worse and worse, not better.

I'm not a doctor, just had a close family member with a malformation there
which was corrected with surgery. You should really see a specialist!

~~~
gentleman11
Interesting. What sort of specialist knows about that?

~~~
ehnto
In my family members case, an orthopaedic surgeon diagnosed the issue, but a
neuro surgeon was required to confirm the diagnosis and eventually perform the
surgery.

The issue they had is known as a Chiari Malformation.

[https://www.ninds.nih.gov/Disorders/Patient-Caregiver-
Educat...](https://www.ninds.nih.gov/Disorders/Patient-Caregiver-
Education/Fact-Sheets/Chiari-Malformation-Fact-Sheet)

~~~
gentleman11
Thanks for the info

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rongenre
After hearing Michael Pollan's interview on NPR and hearing about caffeine's 6
hour half life, I stopped cold turkey. It really has done wonders for my
middle-aged insomnia.

~~~
arafa
It depends on how fast a caffeine metabolizer you are. I've been classified in
genetic testing (whatever the reliability of that is) as a fast metabolizer,
and I can have a full cup of coffee 2-3 hours before bed and not stay up.
Other folks who I know that got slow metabolizer on the test can't have
caffeine after noon without it affecting their sleep (maybe this is the case
for you).

~~~
nishmastime
I've drank my first coffee of the day and immediately suffered an intense
desire to nap. Coffee just isn't a very intense tool for the job.

~~~
smw
I've read that one of the symptoms of ADD is the reaction to stimulants.
Specifically, they tend to have a calming effect instead of the typical jolt
of awareness.

~~~
rootusrootus
Oh, that would explain so, so much.

------
dzink
As a solo developer of my own company I pay the price of my own bad decisions
every day. A night with proper sleep opens the deepest parts of the brain with
strong executive thinking, ability to see alternative solutions to problems,
and better personality and attitude. I’ve come to a point where I wouldn’t let
myself code if I catch myself wanting to watch movies (hint that my mind needs
sleep) and would take a quick nap instead. Even 20 minutes of extra sleep when
sleep deprived brings a different mind to the table. There are plenty of times
when long coding sessions are necessary, but if you’ve had one sleep debt is
the first that needs paid so your brain can actually move your codebase
forward instead of introducing more problems.

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dr_dshiv
"The discovery of CSF is attributed to Emanuel Swedenborg (1688-1772), who had
graduated from the University of Upsala, Sweden, with a degree in mining and
engineering (Fig. 1), Working as a mining engineer, Swedenborg often came
across an underground stream of water that lead him to search for its source.
As a religious man and a teacher of theology, he took upon himself to search
for the seat of the soul. His search for the soul brought him into contact
with anatomists in France, Germany, and Italy. Having observed and
participated in numerous dissections between 1736 and 1740, he felt prepared
to engage in original medical investigations of the brain, which seemed a
likely seat of the soul."

~~~
kzrdude
If he had known what we know now, for example the amount of energy the brain
uses, it would have seemed like an even more fantastic device to him (and
clearly the seat of the soul).

------
airstrike
Link to the study:
[https://science.sciencemag.org/content/366/6465/628](https://science.sciencemag.org/content/366/6465/628)

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pstuart
Sleep deprivation is physical torture.

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omgwtfbyobbq
This reminds of of a paper a read a couple years ago.

[https://mdedge-files-live.s3.us-
east-2.amazonaws.com/files/s...](https://mdedge-files-live.s3.us-
east-2.amazonaws.com/files/s3fs-
public/issues/articles/content_74_Suppl_1_SI-128.pdf)

There's also some recent papers on how the glymphatic system differs in people
with iNPH

[https://academic.oup.com/brain/article/140/10/2691/4085293](https://academic.oup.com/brain/article/140/10/2691/4085293)

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124518/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124518/)

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6609364/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6609364/)

I suspect some of what we see as singular disorders (Alzheimers, etc...) now
will eventually be seen as sets of other distinct disorders.

------
clSTophEjUdRanu
I've always wondered why we need to be unconscious for our brains to recover?
Seems like a huge weakness to let your defenses down for so long. And all
animals do it! You'd think there would be a huge evolutionary incentive to
find a workaround.

~~~
zoomablemind
The body and mind need to slow down to free up time slices for cleaning up the
waste. Humans "in wild" are mostly daytime creatures, that's when they're
supposed to actively look for food, deal with danger, maybe compete for mates,
handle the offsprings. So not much safety to slow down in daytime.

On the other hand, nighttime affords this naturally, though modern society
arguably blurrs the utility and safety aspect of nighttime.

Counterexample is some marine mammals, like dolphins and seals, which can
shutdown half of their brain for sleep, while the other one is active for
safety reasons.

------
bavell
> The findings [...] are the first to suggest that the brain’s well-known ebb
> and flow of blood and electrical activity during sleep may also trigger
> cleansing waves of blood and CSF

Oops, I guess the article or researchers missed the prior work on this
subject... here's a TED Talk from 6 years ago about this exact mechanism (much
more informative than the article):
[https://youtu.be/b8uvrdBrdR4](https://youtu.be/b8uvrdBrdR4)

Gotta say though, I'm ecstatic more research is being done in this area and I
wholeheartedly support their efforts!

------
CodeCube
I wish the article had discussed a few more details about this "rinse cycle",
such as when exactly in the sleep cycle is it that this happens? REM?

~~~
toomuchtodo
Non-REM.

> By studying 11 people as they slept, Lewis and her team identified three
> parts to the rinse cycle. First, there is electrical activity that’s
> definitive of slow wave sleep. Then neurons “go quiet” as Lewis puts it,
> blood volume within the brain decreases, and cerebral spinal fluid flows
> upwards. This flow happens about every 20 seconds during slow wave sleep,
> according to the study.

[https://www.inverse.com/article/60583-sleep-rinse-cycle-
alzh...](https://www.inverse.com/article/60583-sleep-rinse-cycle-alzheimer-s-
toxins)

~~~
kamranahmedse
The paragraph you linked doesn't conclude to Non-REM though

~~~
toomuchtodo
Slow wave sleep is non-REM [1]. Sorry, should've done the extra legwork and
included that as part of the comment you replied to.

[1]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824210/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824210/)

------
1-6
I wonder how important this function is with physical posture during sleep.
Does this affect people who fly coach often and do their sleep prone?

~~~
DrAwdeOccarim
Yea, I've wondered this exact thing. My guess is yes, but it depends on grade
of incline. You also need to compare to supine and if there are other dramatic
sleep interferences due to GERD or sleep apnea that would make supine worse in
other ways.

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hnburnsy
Watch the latest episode of Nova, Mysteries of Sleep, lots of good stuff like
this.

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efiecho
Besides for the headline, there is no mention of this "rinse cycle" only
happening if sleeping during night. People sleeping the entire day instead,
also experience the "rinse cycle".

------
partingshots
Does meditation have the same effect?

~~~
Florin_Andrei
One anecdote you keep hearing about some very advanced practitioners is that
they sleep less, with no apparent ill effects. Perhaps that's worth
investigating.

~~~
MrBuddyCasino
People on a Ketogenic diet report need only 6 hours of sleep with no adverse
effects. I am on Keto plus I also meditate, and I currently sleep 4-5 hours a
night, but I'm feeling awake and refreshed. This is both awesome as I used to
be an owl, and it freaks me the hell out. This is completely unreal, and I
wonder if its going to last or if it is just the usual temporary keto insomnia
due to disrupted melatonin synthesis. It needs glucose and takes a while to
adapt (Glucose -> L-Tryptophan -> Serotonin -> Melatonin).

~~~
pault
Anecdotally, I experience the same thing when I'm on keto. I have much more
energy during the day and I'm not groggy in the morning. Otherwise, it's
nearly impossible for me to wake up even if I've had 8+ hours of sleep, and I
often sleep through my alarm.

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artur_makly
its the deep BASS bombs that killed my sleep cycle a few years ago:
[https://www.ncbi.nlm.nih.gov/pubmed/15273026](https://www.ncbi.nlm.nih.gov/pubmed/15273026)

it just permeates through every surface.. you literally go nuts after a few
nights. I finally had to move to lovely Patagonia.

------
k__
Cool.

If sleep is something chemical it may be easier to improve than if it was
something psychological/neurological.

------
markus_zhang
If someone could make a machine that allows us to only sleep 4 hours per night
but provides the same benefit of a full rested 8-hour sleep, I'd shout TAKE MY
$$.

I envy those who can actually pull this out due to some genes. Lucky
bastards...

------
nikofeyn
i don't trust this plane at all and can barely trust boeing's other planes
now. i certainly don't trust the FAA or beoing themselves. this essentially
amounts to a government bailout by the FAA. from their language on their own
website, the FAA seems to be minimizing the widely publicized internal issues
at boeing that led to the 737 max. is there a way to submit complaints or
comments to this process, given the FAA is a public, government organization?

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allovernow
I'm surprised to see no mention of the recently discovered glymphatic
system[0] which is responsible for this rinsing. Very much looking forward to
research into drugs which modulate the function of the glymphatic system, as
they could potentially solve one of my most difficult life problems, sleep.

It's crazy that we only recently discovered such a critical and [physically]
widespread biological component. Makes me wonder what other "obvious" things
we've yet to stumble upon.

0\.
[https://en.m.wikipedia.org/wiki/Glymphatic_system](https://en.m.wikipedia.org/wiki/Glymphatic_system)

~~~
nomel
This is a negative view of it, but it makes me wonder what the culture is in
the biological and medical fields. Is there a resistance to new concepts?

~~~
jacobrobbins
while technology is very advanced it still has a lot of limits. Watching what
is happening in someone's brain without damaging them is quite difficult. From
the article "Currently, people who volunteer for such experiments have to be
able to fall asleep while wearing an electroencephalogram (EEG) cap inside of
a noisy MRI machine—no easy feat." So it would seem that studying internal
brain activity during healthy sleep is indeed a challenge.

~~~
hamilyon2
Imagine some years into future we will find that sleep does not work the way
we thought because all data was from selected few unnormal enough to be able
to sleep inside mri machine.

