What Happens To Your Brain While You Sleep

Ever wondered what the brain does while we sleep? We did a little digging around and found some interesting results we thought were rather fascinating.

While the brain sleeps, it clears out harmful toxins, a process that may reduce the risk of Alzheimer's, researchers say.

During sleep, the flow of cerebrospinal fluid in the brain increases dramatically, washing away harmful waste proteins that build up between brain cells during waking hours, a study of mice found.

Dr Nedergaard refers to it like a “dishwasher.” He is a professor of neurosurgery at the University of Rochester and an author of the study in Science.

The results appear to offer the best explanation yet of why animals and people need sleep. If this proves to be true in humans as well, it could help explain a mysterious association between sleep disorders and brain diseases, including Alzheimer's.

The scientists noticed that with mice during sleeping. The system that circulates cerebrospinal fluid through the brain and nervous system was "pumping fluid into the brain and removing fluid from the brain at a very rapid pace," Nedergaard says.

The team discovered that this increased flow was possible in part because when mice went to sleep, their brain cells actually shrank, making it easier for fluid to circulate. When an animal woke up, the brain cells enlarged again and the flow between cells slowed to a trickle. "It's almost like opening and closing a faucet," Nedergaard says. "It's that dramatic."

Nedergaard's team had previously shown that this fluid was carrying away waste products that build up in the spaces between brain cells. 

The process is important because what's getting washed away during sleep are waste proteins that are toxic to brain cells, Nedergaard says. This could explain why we don't think clearly after a sleepless night and why a prolonged lack of sleep can actually kill an animal or a person.

There is also evidence to believe this cleaning process has something to do with why we don’t remember certain details the night after we wake up. 

According to neuroscientist, Dr Caroline Leaf, information that was read or heard but not fully understood by the brain nor discussed, the chances of forgetting most of that information after a night of sleep greatly increases.

The brain-cleaning process has been observed in rats and baboons, but not yet in humans. Even so, it could offer a new way of understanding human brain diseases including Alzheimer's. That's because one of the waste products removed from the brain during sleep is beta amyloid, the substance that forms sticky plaques associated with the disease.

That's probably not a coincidence. "Isn't it interesting that Alzheimer's and all other diseases associated with dementia, they are linked to sleep disorders," says Dr Nedergaard.

The report also offers a tantalizing hint of a new approach to Alzheimer's prevention. Based on this bit of information, it does raise the possibility that one might be able to actually control sleep in a way to improve the clearance of beta-amyloid and help prevent amyloidosis that they think can lead to Alzheimer's disease.

We think perhaps all they really need is a new quality mattress so that they get the best sleep possible. As “they” say, prevention is better than cure!