Sleep flushes out brain toxins
A study suggests that a good night’s sleep is the brain’s “waste removal system” that flushes out toxins from a day’s worth of thinking.
Researchers from the University of Rochester Medical Centre showed that brain cells shrink during sleep to open up the gaps between neurons and allow fluid to wash the brain clean. Neglecting to do the cleaning, they say, may lead to brain disorders.
“The brain only has limited energy at its disposal and it appears that it must choose between two different functional states – awake and aware or asleep and cleaning up,” said researcher Dr Maiken Nedergaard to the BBC.
“You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can’t really do both at the same time.”
They found that the brain had a glymphatic system that carries waste material out of the brain. Scientists, who imaged the brains of mice, showed that the glymphatic system became 10-times more active when the mice were asleep.
Cells in the brain, probably the glial cells which keep nerve cells alive, shrink during sleep. This increases the size of the space, the gaps between brain tissue, allowing more fluid to be pumped in and wash the toxins away.
Dr Nedergaard said this was a “vital” function for staying alive, but did not appear to be possible while the mind was awake.
She told the BBC: “This is purely speculation, but it looks like the brain is losing a lot of energy when pumping water across the brain and that is probably incompatible with processing information.”
She added that the true significance of the findings would be known only after human studies, but doing similar experiments in an MRI machine would be relatively easy.
Dr Raphaelle Winsky-Sommerer, a lecturer in sleep at Surrey University, said to the BBC: “It’s not surprising, our whole physiology is changing during sleep.
“The novelty is the role of the interstitial space, but I think it’s an added piece of the puzzle not the whole mechanism.
“The significance is that, yet again, it shows sleep may contribute to the restoration of brain cell function and may have protective effects.”
Many conditions which lead to the loss of brain cells such as Alzheimer’s or Parkinson’s disease are characterised by the build-up of damaged proteins in the brain.
Category: Features, Wellness and Complementary Therapies
