The fundamental reason why we sleep has, up until now, been the presumption that our bodies need time to rest and repair. But a study has shed new light on the integral role sleep plays for our brains.
Published this week in the journal Science, the US research found that brain cells contract during sleep, which creates gaps between neurons in the brain, allowing fluid to wash the organ and remove built-up waste.
Essentially, researchers say this ‘waste removal system’ is at the heart of why our bodies need sleep.
Failure to clear away toxic proteins that build up during thinking could also explain the cause of some degenerative 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, from the University of Rochester Medical Centre.
“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.”
The recent discovery came off the back of previous research into the brain’s glymphatic system – a network of ‘plumbing pipes’ that carry waste materials away from the brain.
The scientists observed the brains of mice and found this waste-removal system was ten times more active during sleep.
Dr Nedergaard believes the glymphatic system is vital to keeping us alive but doesn’t believe that the system is able to function when awake.
“”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 told reporters.
The researchers cautioned that the real significance of their study would only be understood once human studies were conducted. But the findings could provide another missing piece in the puzzle for understanding the brain’s ability to restore and self-repair and shed light on conditions such as Alzheimer’s and Parkinson’s disease.