The incredible science of the sleeping brain

Science Weekly

The Guardian

Science

4.2 • 1K Ratings

🗓️ 2 June 2026

⏱️ 15 minutes

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Summary

Humans have been wondering why we sleep for thousands of years. Is sleep’s purpose rest and relaxation, memory consolidation or maybe cognitive processing? In the last 15 years, scientists have discovered another possible explanation – waste disposal. In 2012 neuroscientist Maiken Nedergaard’s lab discovered that the brain has its own cleaning process, the glymphatic system, which clears away unhelpful proteins and metabolic byproducts, and only switches on at night. Since that groundbreaking discovery we’ve learned more about what drives this system and, importantly, how it could be impacting dementia. To understand more, Ian Sample talks to Prof Nedergaard about how she made the original discovery and how subsequent work is building a picture of sleep as anything but a quiet and inactive state. Help support our independent journalism at theguardian.com/sciencepod

Transcript

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0:00.0	This is The Guardian.
0:02.0	For thousands of years, humans have pondered the question, why do we sleep?
0:16.0	Sleep is still one of the biggest mystery in biology, and we still do not know why it is so important to sleep.
0:25.1	It puts us in such a vulnerable state,
0:27.6	and yet it's vital to life for almost all animals.
0:31.9	I think we all feel on our body on a daily level
0:35.9	how much sleep actually matter for our performance and our well-being
0:40.4	the following day.
0:42.9	Hypotheses about sleep's purpose have changed as we learn more from rest and recovery for the
0:48.6	body to consolidating memory in the brain.
0:52.2	But according to neuroscientist Mike and Nadergaard,
0:55.0	it goes even further.
0:57.6	We now realize the sleep is so much more than that,
1:00.9	and there are probably many both immune action,
1:05.0	many housekeeping function that's going on in sleep,
1:08.2	and it's not all about memory performance.
1:11.3	As we understand more about the biology of sleep, its importance is becoming clearer.
1:17.7	And it turns out that sleep disruption could have major consequences for our future brain health.
1:34.6	So today, the incredible science of the sleeping brain and why it all comes down to good housekeeping. From The Guardian, I'm Ian Sampbell, and this is Science Weekly.
1:45.8	Mike and Nadergaard, you're Professor of Neuroscience at Rochester Medical School and at the
1:51.9	University of Copenhagen.
1:53.9	And back in 2012, your lab was behind the groundbreaking discovery of this mechanism the
	...

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