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Sleep does not help brain wash out toxins, study suggests

theguardian.com

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Re: Sleep does not help brain wash out toxins, study suggests

#11

Post by coldtea »

freddie_mercury wrote: post #9
lambdaba wrote: post #3

What about this? Sleep Drives Metabolite Clearance from the Adult Brain (2014) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880190/ > Using real-time assessments of tetramethylammonium diffusion and two-photon imaging in live mice, we show that natural sleep or anesthesia are associated with a 60% increase in the interstitial space, resulting in a striking increase in convective exchange of cerebrospinal fluid with…

That paper is referenced in the one linked. The authors are not unaware of it.

And?

Does it succesfully refute it?

Or is the new study just another study with bad methodology that wont be replicating?

Or maybe the first one is?

Individual studies aren't worth considering, especially after they just came out. Call me when they have settled about it, 10+ years from now.

Re: Sleep does not help brain wash out toxins, study suggests

#12

Post by coldtea »

olig15 wrote: post #2

Obviously the article leave a lot of the science out, but this sounds like it’d be an easy thing to test for (which they’ve now done). Why wouldn’t this have been done years ago - I’m not trying g to say they should have done it earlier, as I genuinely don’t know. Is the tech to check this new? How much other science has been based off of this theory in the meantime?

Did they test it succesfully? Did they make some blunder? Did they misrepresented the importance of their results? Will it replicate? Does it apply to humans?

I wouldn't be bothered with putting much faith on any of the papers coming out, unless I was a researcher in that space. The dust is far from settled.

Re: Sleep does not help brain wash out toxins, study suggests

#13

Post by lm28469 »

keepamovin wrote: post #6
lambdaba wrote: post #3

What about this? Sleep Drives Metabolite Clearance from the Adult Brain (2014) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880190/ > Using real-time assessments of tetramethylammonium diffusion and two-photon imaging in live mice, we show that natural sleep or anesthesia are associated with a 60% increase in the interstitial space, resulting in a striking increase in convective exchange of cerebrospinal fluid with…

Exactly, the flushing effect. Which you can also feel when you do some forms of meditation :)

You have no physical sensors that would allow you to "feel" events up there.

Re: Sleep does not help brain wash out toxins, study suggests

#14

Post by wzdd »

coldtea wrote: post #11
freddie_mercury wrote: post #9

Earlier quoted context omitted.

That paper is referenced in the one linked. The authors are not unaware of it.

And? Does it succesfully refute it? Or is the new study just another study with bad methodology that wont be replicating? Or maybe the first one is? Individual studies aren't worth considering, especially after they just came out. Call me when they have settled about it, 10+ years from now.

The way they refute it is interesting.

> Those authors observed that fluorescent dyes injected into the cerebrospinal fluid (CSF) via the cisterna magna penetrated further into the cortex during sleep and anesthesia. They interpreted this as showing that molecular movement into the cortex must be faster during these states. However, the concentration of dye in any brain region will always be the difference between its rate of arrival and its rate of departure and so increased dye penetration in sleep and anesthesia can be equally well explained by a reduced rate of clearance rather than an increased rate of entry.

So the previous paper assumed that the presence of dye further into the brain meant more clearance, but these authors point out that the presence of more dye could mean less clearance (because if the fluid isn't being replaced as quickly the dye can simply diffuse further). The previous authors also injected dye into the CSF, which complicates matters as the CSF is moving both into and out of the brain all the time.

However:

> Our data in Figs. 2 and 3 show that, averaged across the brain, clearance is reduced by both sleep and anesthesia

... if you just focus on average dye concentration in the brain, and you inject the dye directly into the brain (the parenchyma) rather than into the CSF, the mean concentration is higher after a period of sleep than it is after a period of wakefulness. Which suggests less clearance, rather than more clearance, during sleep.

Re: Sleep does not help brain wash out toxins, study suggests

#16

Post by adammarples »

lm28469 wrote: post #13
keepamovin wrote: post #6

Earlier quoted context omitted.

Exactly, the flushing effect. Which you can also feel when you do some forms of meditation :)

You have no physical sensors that would allow you to "feel" events up there.

by what sense does one 'feel' tired?

Re: Sleep does not help brain wash out toxins, study suggests

#18

Post by Lutger »

lm28469 wrote: post #13
keepamovin wrote: post #6

Earlier quoted context omitted.

Exactly, the flushing effect. Which you can also feel when you do some forms of meditation :)

You have no physical sensors that would allow you to "feel" events up there.

Not literally, though 'feeling' does a lot of work in that sentence and rightly so. You don't exactly have a physical sensor to 'feel' sad either, which also happens up there mostly, but still people usually accept that we can 'feel' the experience of sadness.

Becoming aware of mental states influencing perception is how you register events up there (using meditation), which is what 'feeling' means in this context.

Re: Sleep does not help brain wash out toxins, study suggests

#20

Post by lukan »

coldtea wrote: post #11
freddie_mercury wrote: post #9

Earlier quoted context omitted.

That paper is referenced in the one linked. The authors are not unaware of it.

And? Does it succesfully refute it? Or is the new study just another study with bad methodology that wont be replicating? Or maybe the first one is? Individual studies aren't worth considering, especially after they just came out. Call me when they have settled about it, 10+ years from now.

What are the practical implications anyway?

Sleep is good and lack of sleep is bad, I think that is a pretty established fact already.

And this is important basic research, but I do not see how it would influence me personally.

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