
Glymphatic system clears toxins in the brain during sleep (2013) - appwiz
https://www.urmc.rochester.edu/news/story/3956/to-sleep-perchance-to-clean.aspx
======
jjjensen90
Really interesting 3 part podcast with an MD and a neuroscientist sleep expert
[https://peterattiamd.com/matthewwalker1/](https://peterattiamd.com/matthewwalker1/)

They dicsuss the glymphatic system's role in sleep, the many many detrimental
effects of sleep too little sleep, the link between sleep and Alzheimer's, and
all sorts of awesome stuff.

I actually got a sleep study and was diagnosed with sleep apnea after I
listened to this episode and had the wits scared out of me about my sleep
hygeine. :)

~~~
perl4ever
I was suffering from extreme daytime sleepiness that was impacting my job, and
I got a sleep study and was told I _didn 't_ have sleep apnea and melatonin
was suggested which didn't have a perceptible effect.

Even prior to that, for all of my adult life, my sleep habits had not been
normal; I always felt like staying up longer and sleeping longer, and waking
up for scheduled things was painful, but having commitments like work or
appointments was the only way I _could_ force myself to get up.

By accident, I found out my friend was taking bupropion, and I asked my doctor
about it, and once I started taking it, my sleep cycle is practically normal.
I have no idea why, but it was almost magical. Bupropion is sold as both a
smoking cessation drug and an antidepressant, and it seems to do something to
nicotinic receptors (of course) and to norepinephrine.

Edit: and caffeine never helped me; I only developed a tolerance and then when
I stopped drinking coffee on weekends I would feel even worse than usual.

~~~
rajlego
Something that really bothers me about coffee culture is that coffee is seen
as a solution to being tired when really all it is is just an alertness
booster. The main neurological cause of sleepiness is the brain’s desire to do
memory optimization which can only happen by sleeping at the right time.
Correct timing is really important and it seems to me like you have DSPS
(delayed sleep phase syndrome). Most people’s circadian rhythms are a bit
longer than 24 hours (usually between 24.5-25.5 hours) though external signals
like exercise or bright light in the morning reset it to being closer to 24.
If you have DSPS, yours isn’t reset well (you can try the aformtentioned
morning bright light and exercise to change this) and you have a tendency to
wake up later and later each day. The problem is that if you have to wake up
at 7 every day and you think you need 9 hours of sleep you’ll try to sleep at
10 to get enough which backfires. The reason it can backfire is that for good
sleep you need both strong homeostatic sleep signals (tiredness from thinking
a lot or doing a lot of effort in the day) and circadian (sleepiness goes and
comes cyclically). If you sleep at 10 and have DSPS, even if your homeostatic
signals sleep, it is likely that your circadian isn’t which means you end up
tossing and turning throughout the night. If you slept maybe an hour later
you’d get full circadian and homeostatic sleepiness giving you good quality
sleep but if you have to wake up at 7 you have to cut short sleep with an
alarm clock which isn’t great since your brain can’t complete all the memory
optimization it wants. I would say though that sleeping later more restfully
for shorter will do you better than sleeping earlier restlessly. (Sorry for
the essay, sleep is something I care about a lot. I hope this was a little
helpful.)

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barbs
Sometimes after sleeping, especially after a good night's sleep, I have a
feeling that my brain has been scrubbed clean. It physically feels "fresh",
similar to the feeling of having brushed my teeth. Not totally sure if it's
not just my imagination, but I like to think there's some science behind it :)

~~~
emerongi
If I sleep really long I get a buzz in my head. I've never done drugs, but it
kind of feels like what I think being high would be. Sort of like a brain-
orgasm.

It feels really good for about 4 hours, then disperses.

~~~
collyw
I am assuming "never done illegal drugs" is probably what you mean.

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sak5sk
Does this "waste" accumulate indefinitely if you are constantly lacking sleep,
or does it get flushed out in full every night you get a good night's sleep?
So say I had a crappy sleep schedule for 3 days, but on the 4th day I slept a
lot and feel very rested. Did the last night's cleaning take care of all the
accumulated waste?

~~~
DoreenMichele
Articles and studies I've seen suggest that it takes more than one night to
get caught up and that some things become seriously intractable if you are
routinely short of sleep.

~~~
radium3d
That's interesting, I wonder if this harvard study on "catching up on sleep"
accidentally shows in some way how much sleep is required to flush out the
toxins? They stated, "10-hour sleep opportunities consistently restored
vigilance task performance during the first several hours of wakefulness."

[https://stm.sciencemag.org/content/2/14/14ra3.abstract](https://stm.sciencemag.org/content/2/14/14ra3.abstract)

~~~
DoreenMichele
I looked at the link. They actually were also having people stay up longer, so
I don't think you can conclude that.

The brain also "resets" during sleep. As part of that process, it shrinks
substantially.

Aa you do stuff during the day, synapses swell as they see repetitive use of
the same pathways. This reinforces those ideas or actions, crowding out other
things. In order to restore short term memory formation and the ability to
learn new things, your brain has to reset at night.

There's also interesting research on two proteins, amyloid and tau, that
accumulate faster when people are sleep deprived. They are both associated
with Alzheimer's.

One of them rapidly resolves when you get caught up on sleep again. The other
doesn't.

~~~
robert_tweed
Do you have any references for synapses changing size with use? A quick google
indicates the opposite, if anything:

[http://blogs.discovermagazine.com/neuroskeptic/2015/06/08/br...](http://blogs.discovermagazine.com/neuroskeptic/2015/06/08/brain-
bigger-in-the-morning/)

Brain expansion (not contraction) overnight is unexplained, but may be due to
fluid retention. That definitely affects the spine - causing us to be slightly
taller and less flexible in the morning.

~~~
DoreenMichele
_Striking electron microscope pictures from inside the brains of mice suggest
what happens in our own brain every day: Our synapses – the junctions between
nerve cells – grow strong and large during the stimulation of daytime, then
shrink by nearly 20 percent while we sleep, creating room for more growth and
learning the next day._

[https://neurosciencenews.com/sleep-brain-
reset-6047/](https://neurosciencenews.com/sleep-brain-reset-6047/)

Sleep Shrinks the Brain--and That's a Good Thing

Without a nighttime reset, synapses could burn out like an outlet with too
many appliances plugged in

[https://www.scientificamerican.com/article/sleep-shrinks-
the...](https://www.scientificamerican.com/article/sleep-shrinks-the-brain-
and-thats-a-good-thing/)

 _The sleeping and the anesthetized mice had a 60% increase in the volume of
fluid, apparently because brain cells actually shrink to allow more space in
the channels. When the researchers woke the mice up, the flow of fluid into
the brain abruptly slowed._

[http://m.nautil.us/blog/sleep-when-brain-cells-shrink--
neuro...](http://m.nautil.us/blog/sleep-when-brain-cells-shrink--neuro-trash-
is-flushed-away)

~~~
robert_tweed
Interesting, thanks.

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andrewvc
Sleeping on one's right side can exacerbate acid reflux (which can increase
your risk for throat / esophageal cancer).

So, taken together with this, sleeping on the left side seems ideal.

~~~
technofiend
Particularly if you suffer from diverticulitis as I do, putting pressure on
the left side seems to lessen or calm spasms.

~~~
thinkingemote
Most diverticulitis occurs on the left side in the West and the right side in
the East.

~~~
technofiend
Really? I thought the lower sigmoid colon was in the same place on everyone.
Does that mean some other part of the digestive tract is stressed to the point
of forming diverticulae in an Eastern diet?

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tylerjwilk00
To maximize glymphatic toxin clearing the lateral sleeping position is
currently recommended.

1\. [https://neurosciencenews.com/lateral-sleep-position-
neurolog...](https://neurosciencenews.com/lateral-sleep-position-
neurology-2363/amp/)

2\.
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4524974/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4524974/)

~~~
quickthrower2
That’s the side position. Lucky for me I sleep that way to make my head
comfortable. I wonder if it is more refreshing to sleep that way too then?

~~~
teej
If I sleep anywhere but my side, my throat tries it’s darndest to choke me to
death, on behalf of the sleep apnea. So it works great for me!

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ghego1
I am not an expert, so I might be missing something, but is this related to
the finding that was reported in 2014 [1]? Is it the new development that now
they have actually observed the glymphatic system at work?

[1]
[[https://www.nytimes.com/2014/01/12/opinion/sunday/goodnight-...](https://www.nytimes.com/2014/01/12/opinion/sunday/goodnight-
sleep-
clean.html\]\(https://www.nytimes.com/2014/01/12/opinion/sunday/goodnight-
sleep-clean.html\))

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celticmusic
I've believed this to be true for a while now, as I've gotten older this has
gotten obvious to me.

When you're younger everything works so well you don't notice the subtle
differences often times. But as I've rounded 40 I've realized just how big a
difference good sleep can make.

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rl3
After having three concussions in the past two years, one just recently—I've
taken a keen interest in learning as much as I can about mild traumatic brain
injury (mTBI).

Impairment of glial-lymphatic function is thought to play a role in all manner
of neurodegenerative disease, including TBI and mTBI.[0][1][2]

My potentially incorrect layperson oversimplification:

mTBI in particular is broadly characterized as a loss of homeostasis within
the brain, more specifically metabolic dysregulation secondary to primary
mechanical injury. When you suffer a concussion, an inflammatory response
occurs within the brain. This is useful in the acute phase of injury, but can
lead to chronic neuroinflammation if not properly mediated. Oxidative stress
secondary to the primary injury can interfere with this process, and what you
end up with is a complex biochemical cascade that furthers metabolic
dysregulation and loss of homeostasis, resulting in latent neurodegeneration
(brain damage). Among those systems impacted by said dysregulation is the
glymphatic system.

Traumatic Brain Injury (TBI) by contrast is a term used to describe brain
injury more severe than that of a simple concussion. It's basically everything
mTBI is and then some: compromised blood–brain barrier, immune cell
infiltration, necrosis, sometimes direct mechanical destruction of brain
tissue in the case of open head injuries. It's typically quite horrific.

In researching the topic, I've noticed many papers suggest pathologies from
Alzheimer's and Parkinson's to CTE may in fact stem from chronic loss of
[metabolic] homeostasis within the brain. Whether that's from chronically poor
sleep, or hits to your head, the end result is disturbingly similar.

In my own experience, the number one thing that has helped me recover after a
concussion has been sleep. Usually following an injury I need more of it than
normal. It's not hard to imagine the glymphatic system plays a critical role
in healing.

[0]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261373/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261373/)

[1]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034172/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034172/)

[2]
[https://www.ncbi.nlm.nih.gov/pubmed/28859995](https://www.ncbi.nlm.nih.gov/pubmed/28859995)

