Ian Sample

It's a research opportunity.

And then you see the VAR.

Sometimes it gives you an extra cheer.

Sometimes you just have your head in your hands again and you are cursing VAR as the devil's technology.

And we have a long period to see how this goes now with the World Cup.

It's a research opportunity.

This is The Guardian.

For thousands of years, humans have pondered the question, why do we sleep?

It puts us in such a vulnerable state, and yet it's vital to life for almost all animals.

Hypotheses about sleep's purpose have changed as we learn more, from rest and recovery for the body to consolidating memory in the brain.

But according to neuroscientist Maiken Nedegaard, it goes even further.

As we understand more about the biology of sleep, its importance is becoming clearer.

And it turns out that sleep disruption could have major consequences for our future brain health.

So today, the incredible science of the sleeping brain and why it all comes down to good housekeeping.

From The Guardian, I'm Ian Sample, and this is Science Weekly.

Michael Nadergaard, you're Professor of Neuroscience at Rochester Medical School and at the University of Copenhagen.

And back in 2012, your lab was behind the groundbreaking discovery of this mechanism the brain has for clearing out its waste, which you named the glymphatic system.

So first of all, what does this cleaning system have to do with sleep?

Right, so unlike every other organ, the brain can only clean out its waste molecules, proteins like amyloid and tau and metabolic byproducts while we're sleeping, which provides a clue as to what sleep might be for.

And this process all centers on what's happening to the fluid that surrounds the brain, the cerebrospinal fluid.