One more reason to get a good night’s sleep | Jeff Iliff

Translator: Pablo Figueiredo Palacios Reviewer: Serv. de Norm. Lingüística U. de Santiago de Compostela

Sleep.

Durmir.

It's something we spend about a third of our lives doing,

Algo ao que lle dedicamos preto dun terzo da nosa vida

but do any of us really understand what it's all about?

mais algún de nós realmente sabe de que se trata?

Two thousand years ago, Galen,

Hai dous mil anos, Galeno,

one of the most prominent medical researchers

un dos investigadores médicos máis destacados da Antigüidade

of the ancient world,

proposed that while we're awake,

postulou que mentres estamos espertos,

our brain's motive force, its juice,

a forza motriz do cerebro, o seu zume,

would flow out to all the other parts of the body,

fluía cara a todas as outras partes do corpo

animating them but leaving the brain all dried up,

animándoas pero deixando o cerebro seco.

and he thought that when we sleep,

Pensaba que cando durmimos

all this moisture that filled the rest of the body

toda esta humidade que enchía o resto do corpo

would come rushing back,

volvía rapidamente para hidratar o cerebro

rehydrating the brain

and refreshing the mind.

e refrescar a mente.

Now, that sounds completely ridiculous to us now,

Isto hoxe soa totalmente ridículo,

but Galen was simply trying to explain

mais Galeno só trataba de explicar unha cousa sobre o sono

something about sleep

that we all deal with every day.

coa que lidamos a diario.

See, we all know based on our own experience

Todos sabemos, pola nosa experiencia, que durmir aclara a mente

that when you sleep, it clears your mind,

and when you don't sleep,

e non durmir deixa a cabeza turbia.

it leaves your mind murky.

But while we know a great deal more about sleep now

Pese a que hoxe sabemos moitísimo máis sobre o sono

than when Galen was around,

que cando vivía Galeno,

we still haven't understood why it is that sleep,

aínda non comprendemos por que o sono, de todas as nosas actividades

of all of our activities, has this incredible

ten esta incríbel función reparadora para a mente.

restorative function for the mind.

So today I want to tell you about

Así que hoxe quero falar sobre investigacións recentes

some recent research

that may shed new light on this question.

que poden botar luz sobre esta cuestión.

We've found that sleep may actually be

Atopamos que o sono pode ser en realidade

a kind of elegant design solution

unha especie de solución elegante de deseño

to some of the brain's most basic needs,

para algunhas das necesidades máis básicas do cerebro,

a unique way that the brain

un xeito único en que o cerebro

meets the high demands and the narrow margins

resolve as amplas esixencias e as estreitas marxes

that set it apart from all the other organs of the body.

que o fan distinto do resto de órganos do corpo.

So almost all the biology that we observe

Case toda a bioloxía que observamos

can be thought of as a series of problems

pode pensarse como unha serie de problemas

and their corresponding solutions,

e as súas solucións correspondentes.

and the first problem that every organ must solve

O primeiro problema que todo órgano ten que resolver

is a continuous supply of nutrients to fuel

é o do continuo fornecemento de nutrientes para alimentar todas as células do corpo.

all those cells of the body.

In the brain, that is especially critical;

No cerebro é especialmente crítico;

its intense electrical activity uses up

a súa intensa actividade eléctrica emprega

a quarter of the body's entire energy supply,

un cuarto de todo o abastecemento de enerxía do corpo,

even though the brain accounts

a pesar de que o cerebro constitúe só arredor dun 2% da masa total do corpo.

for only about two percent of the body's mass.

So the circulatory system

O sistema circulatorio soluciona o problema de reparto de nutrientes

solves the nutrient delivery problem

by sending blood vessels to supply nutrients

usando vasos sanguíneos, que levan nutrientes e osíxeno

and oxygen to every corner of our body.

a cada recanto do noso corpo.

You can actually see it in this video here.

Podémolo ver neste vídeo.

Estamos a ver os vasos sanguíneos do cerebro dun rato vivo.

Here, we're imaging blood vessels

in the brain of a living mouse.

The blood vessels form a complex network

Os vasos sanguíneos forman unha complexa rede

that fills the entire brain volume.

que enche todo o volume do cerebro.

They start at the surface of the brain,

Comezan na súa superficie e despois penetran no tecido.

and then they dive down into the tissue itself,

and as they spread out, they supply nutrients

A medida que se espallan, levan nutrientes

and oxygen to each and every cell in the brain.

e osíxeno a todas e cada unha das células do cerebro.

Now, just as every cell requires

Dado que todas as células precisan nutrientes para funcionar,

nutrients to fuel it,

every cell also produces waste as a byproduct,

cada célula tamén produce refugallos como subproduto

and the clearance of that waste

e a limpeza deses refugallos é o segundo problema básico

is the second basic problem

that each organ has to solve.

que ten que resolver cada órgano.

This diagram shows the body's lymphatic system,

Este diagrama amosa o sistema linfático,

which has evolved to meet this need.

que evolucionou para satisfacer esta necesidade.

It's a second parallel network of vessels

É unha segunda rede paralela de vasos que se estende ao longo do corpo.

that extends throughout the body.

It takes up proteins and other waste

Recolle as proteínas e outros residuos dos espazos intercelulares

from the spaces between the cells,

it collects them, and then dumps them into the blood

para despois vertelos no sangue e que poidan ser eliminados.

so they can be disposed of.

But if you look really closely at this diagram,

Se mirades ben este diagrama veredes algo

you'll see something

that doesn't make a lot of sense.

que non ten moito sentido.

So if we were to zoom into this guy's head,

Se ampliamos a cabeza deste individuo

one of the things that you would see there

unha das cousas que se ven é que non hai vasos linfáticos no cerebro.

is that there are no lymphatic vessels in the brain.

But that doesn't make a lot of sense, does it?

Mais isto non ten moito sentido, non si?

I mean, the brain is this intensely active organ

Quero dicir, o cerebro é un órgano cunha intensa actividade

that produces a correspondingly large amount of waste

que produce unha cantidade igualmente grande de residuos

that must be efficiently cleared.

que hai que limpar eficazmente.

And yet, it lacks lymphatic vessels, which means that

E aínda así non ten vasos linfáticos, o que significa

the approach that the rest of the body takes

que a solución que adopta o resto do corpo

to clearing away its waste

para limpar os residuos non funciona no cerebro.

won't work in the brain.

So how, then, does the brain solve

Entón como soluciona o cerebro o problema da limpeza dos seus residuos?

its waste clearance problem?

Well, that seemingly mundane question

Esta cuestión, aparentemente trivial,

is where our group first jumped into this story,

é a que motivou ao noso grupo a entrar nesta historia.

and what we found

E o que atopamos ao entrarmos no cerebro,

as we dove down into the brain,

down among the neurons and the blood vessels,

entre as neuronas e os vasos sanguíneos, foi que a solución do cerebro

was that the brain's solution

to the problem of waste clearance,

para o problema da limpeza de residuos era totalmente inesperada.

it was really unexpected.

It was ingenious,

Era enxeñosa pero tamén fermosa.

but it was also beautiful.

Let me tell you about what we found.

Vouvos contar o que atopamos.

So the brain has this large pool

O cerebro ten unha bolsa grande

of clean, clear fluid called cerebrospinal fluid.

de fluído limpo e claro, chamado líquido cefalorraquídeo,

We call it the CSF.

que abreviamos como LCR.

The CSF fills the space that surrounds the brain,

O LCR enche o espazo que rodea o cerebro,

de modo que os residuos do interior do cerebro

and wastes from inside the brain

make their way out to the CSF,

saen cara ao LCR,

which gets dumped, along with the waste, into the blood.

que é vertido no sangue xunto cos residuos.

So in that way, it sounds a lot like

Isto semella moi parecido ao sistema linfático, verdade?

the lymphatic system, doesn't it?

But what's interesting is that the fluid and the waste

Pero o máis interesante é que o líquido mais os residuos

from inside the brain,

do interior do cerebro non chegan así como así

they don't just percolate their way randomly

out to these pools of CSF.

ata as bolsas do LCR.

Instead, there is a specialized network of plumbing

Ao contrario, hai unha rede especializada de condutos

that organizes and facilitates this process.

que organiza e facilita este proceso.

You can see that in these videos.

Podédelo ver nestes vídeos.

Here, we're again imaging into the brain

Aquí estamos vendo outra vez o cerebro de ratos vivos.

of living mice.

The frame on your left shows

A imaxe da esquerda amosa o que sucede na superficie do cerebro,

what's happening at the brain's surface,

and the frame on your right shows

mentres que a da dereita amosa o que ocorre dentro do cerebro,

what's happening down below the surface of the brain

within the tissue itself.

no interior do propio tecido.

We've labeled the blood vessels in red,

Marcamos os vasos sanguíneos en vermello

and the CSF that's surrounding the brain

e o LCR que rodea o cerebro vai aparecer en verde.

will be in green.

Now, what was surprising to us

O que nos sorprendeu foi que o líquido do exterior do cerebro

was that the fluid on the outside of the brain,

it didn't stay on the outside.

non se mantiña no exterior, senón que era bombeado

Instead, the CSF was pumped back into

and through the brain

outra vez cara ao interior do cerebro polo exterior dos vasos sanguíneos

along the outsides of the blood vessels,

and as it flushed down into the brain

e a medida que se filtraba no cerebro polo exterior dos vasos

along the outsides of these vessels,

it was actually helping to clear away,

estaba axudando a desfacerse, a limpar os residuos

to clean the waste from the spaces

dos espazos intercelulares do cerebro.

between the brain's cells.

If you think about it,

Se vos parades a pensalo,

using the outsides of these blood vessels like this

empregar así o exterior dos vasos sanguíneos

is a really clever design solution,

é unha solución de deseño moi intelixente,

because the brain is enclosed

dado que o cerebro está encerrado nun cranio ríxido

in a rigid skull

and it's packed full of cells,

e está repleto de células, non hai espazo dentro del

so there is no extra space inside it

for a whole second set of vessels like the lymphatic system.

para un segundo conxunto de vasos coma o sistema linfático.

Yet the blood vessels,

Mais os vasos sanguíneos si se estenden desde a superficie

they extend from the surface of the brain

down to reach every single cell in the brain,

ata o interior para chegar a todas as células do cerebro,

which means that fluid

o que significa que o líquido que circula polo exterior destes vasos

that's traveling along the outsides of these vessels

can gain easy access to the entire brain's volume,

pode chegar facilmente a todo o volume do cerebro,

so it's actually this really clever way

polo que é unha maneira moi intelixente

to repurpose one set of vessels, the blood vessels,

de facer que un conxunto de vasos, os vasos sanguíneos,

to take over and replace the function

asuma e substitúa a función

of a second set of vessels, the lymphatic vessels,

dun segundo conxunto de vasos, os vasos linfáticos,

to make it so you don't need them.

e evite así que sexan necesarios.

And what's amazing is that no other organ

E o máis impresionante é que ningún outro órgano

takes quite this approach

adopta esta solución para desfacerse dos residuos intercelulares.

to clearing away the waste from between its cells.

This is a solution that is entirely unique to the brain.

É unha solución completamente única do cerebro.

But our most surprising finding

Pero o descubrimento máis sorprendente foi que todo isto,

was that all of this,

everything I just told you about,

todo o que vos acabo de contar, o deste líquido que percorre o cerebro

with all this fluid rushing through the brain,

it's only happening in the sleeping brain.

só ocorre no cerebro durmido.

Here, the video on the left

Aquí, o vídeo da esquerda amosa canto LCR se está a mover

shows how much of the CSF is moving

through the brain of a living mouse while it's awake.

polo cerebro dun rato vivo que está esperto.

It's almost nothing.

Practicamente nada.

Yet in the same animal,

Mais no mesmo animal, se agardamos un pouco a que adormeza,

if we wait just a little while until it's gone to sleep,

what we see is that the CSF

vemos o LCR circular polo cerebro,

is rushing through the brain,

and we discovered that at the same time

e descubrimos que no mesmo momento en que o cerebro comeza a durmir,

when the brain goes to sleep,

as neuronas semellan encoller, abrindo espazos entre elas

the brain cells themselves seem to shrink,

opening up spaces in between them,

e permitindo que o líquido penetre e limpe os residuos.

allowing fluid to rush through

and allowing waste to be cleared out.

Entón parece que Galeno, en realidade, estaba no certo

So it seems that Galen may actually have been

sort of on the right track when he wrote about

fluid rushing through the brain

cando escribía sobre un fluído que percorría o cerebro

when sleep came on.

cando comezabamos a durmir.

Our own research, now it's 2,000 years later,

A nosa investigación, 2000 anos despois, suxire que o que sucede

suggests that what's happening is that

when the brain is awake

é que cando o cerebro está esperto e na súa máxima actividade,

and is at its most busy,

it puts off clearing away the waste

adía a limpeza dos residuos dos espazos intercelulares

from the spaces between its cells until later,

e despois, cando durme e non precisa estar tan activo

and then, when it goes to sleep

and doesn't have to be as busy,

it shifts into a kind of cleaning mode

entra nunha especie de modo de limpeza

to clear away the waste

para desfacerse dos residuos dos espazos intercelulares,

from the spaces between its cells,

the waste that's accumulated throughout the day.

residuos que foron acumulándose durante o día.

So it's actually a little bit like how you or I,

Polo que en realidade é un pouco coma nós,

we put off our household chores during the work week

cando atrasamos as tarefas da casa durante a semana,

when we don't have time to get to it,

cando non temos tempo de facelas,

and then we play catch up on all the cleaning that we have to do

e despois poñémonos ao día e facemos toda a limpeza

when the weekend rolls around.

cando chega a fin de semana.

Now, I've just talked a lot about waste clearance,

Ata agora falei moito sobre a limpeza de residuos,

but I haven't been very specific

mais non fun moi específico sobre os tipos de residuos

about the kinds of waste

that the brain needs to be clearing

que o cerebro ten que eliminar durante o sono para manterse saudábel.

during sleep in order to stay healthy.

The waste product that these recent studies

O residuo en que se centraron os estudos máis recentes

focused most on is amyloid-beta,

é a beta-amiloide,

which is a protein that's made in the brain all the time.

unha proteína que se fabrica no cerebro todo o tempo.

My brain's making amyloid-beta right now,

Agora mesmo o meu cerebro está a producir beta-amiloide

and so is yours.

e tamén os vosos.

But in patients with Alzheimer's disease,

Pero en pacientes con alzhéimer, a beta-amiloide acumúlase

amyloid-beta builds up and aggregates

e concéntrase nos espazos entre neuronas no canto de ser limpada como debería.

in the spaces between the brain's cells,

instead of being cleared away like it's supposed to be,

and it's this buildup of amyloid-beta

E esta acumulación de beta-amiloide cremos que é un dos pasos chave

that's thought to be one of the key steps

in the development of that terrible disease.

no desenvolvemento desta terrible enfermidade.

So we measured how fast amyloid-beta is cleared

Medimos a velocidade con que a beta-amiloide

from the brain when it's awake

é eliminada do cerebro cando está esperto e cando está a durmir,

versus when it's asleep,

and we found that indeed,

e achamos que, efectivamente, a limpeza da beta-amiloide

the clearance of amyloid-beta

is much more rapid from the sleeping brain.

é moito máis rápida no cerebro que está a durmir.

So if sleep, then,

Polo tanto, se o sono é parte da solución que ten o cerebro

is part of the brain's solution

to the problem of waste clearance,

para o problema da limpeza de residuos,

then this may dramatically change how we think

entón pode mudar drasticamente a forma de pensarmos a relación

about the relationship between sleep,

amyloid-beta, and Alzheimer's disease.

entre o sono, a beta-amiloide e a enfermidade de alzhéimer.

A series of recent clinical studies

Algúns estudos clínicos recentes suxiren

suggest that among patients

que entre pacientes que aínda non desenvolveron alzhéimer,

who haven't yet developed Alzheimer's disease,

worsening sleep quality and sleep duration

o empeoramento da calidade e da duración do sono

are associated with a greater amount

están asociadas a unha maior cantidade de beta-amiloide no cerebro.

of amyloid-beta building up in the brain,

and while it's important to point out

Porén, cómpre sinalar que estes estudos non demostran que a falta de sono

that these studies don't prove

that lack of sleep or poor sleep

cause Alzheimer's disease,

ou o sono escaso provoquen a enfermidade de alzhéimer,

pero si suxiren que a dificultade do cerebro

they do suggest that the failure of the brain

to keep its house clean

para manter a súa casa limpa eliminando residuos coma a beta-amiloide

by clearing away waste like amyloid-beta

may contribute to the development

pode contribuír ao desenvolvemento de doenzas como o alzhéimer.

of conditions like Alzheimer's.

Entón, o que esta nova investigación di

So what this new research tells us, then,

is that the one thing that all of you

é que o que todos vós xa sabiades sobre o sono,

already knew about sleep,

that even Galen understood about sleep,

o que incluso Galeno xa sabía, que refresca e despexa a mente,

that it refreshes and clears the mind,

may actually be a big part

pode ser unha parte importante da función do sono.

of what sleep is all about.

Mirade, vós e mais eu durmimos todas as noites

See, you and I, we go to sleep

every single night,

but our brains, they never rest.

mais os nosos cerebros nunca descansan.

While our body is still

Mentres o noso corpo está parado e a nosa mente vaga por aí en soños,

and our mind is off walking in dreams somewhere,

the elegant machinery of the brain

a elegante maquinaria do cerebro está en silencio traballando duro

is quietly hard at work

cleaning and maintaining

limpando e mantendo esta máquina incribelmente complexa.

this unimaginably complex machine.

Like our housework,

Igual que as tarefas de casa, é un labor sucio e ingrato

it's a dirty and a thankless job,

but it's also important.

pero tamén importante.

Na casa, se estamos sen limpar a cociña

In your house, if you stop cleaning your kitchen

for a month,

durante un mes

your home will become completely unlivable

o fogar convértese rapidamente nun lugar no que é imposíbel vivir.

very quickly.

But in the brain, the consequences

Pero no cerebro, as consecuencias de atrasarse na limpeza

of falling behind may be much greater

poden ser moito máis graves que a vergoña de ter os mesados sucios,

than the embarrassment of dirty countertops,

because when it comes to cleaning the brain,

porque cando se trata de limpar o cerebro,

it is the very health and function

son a saúde e a función da mente e do corpo as que están en xogo;

of the mind and the body that's at stake,

which is why understanding these

e por iso comprender hoxe

estas funcións básicas de mantemento do cerebro

very basic housekeeping functions of the brain today

may be critical for preventing and treating

pode ser crucial para previr e tratar doenzas da mente o día de mañá.

diseases of the mind tomorrow.

Thank you.

Grazas.

(Aplauso)

(Applause)