A new study concludes that sleep helps keep the brain free of toxins.
According to researchers, while we sleep the brain uses this period to eradicate any waste toxins that build up during the course of a day when the brain is active.
"We have a cleaning system that almost stops when we are awake and starts when we sleep. It's almost like opening and closing a faucet -- it's that dramatic," says researcher Dr Maiken Nedergaard, co-director of the Center for Translational Neuromedicine at the University of Rochester Medical Center.
The study, published in the journal Science, shows that neural waste is primarily active when our body is resting. Cells in the brain (probably the glial cells) apparently shrink in size when one is sleeping, which in turn aids in opening up the gaps between neurons and allow for fluid to clean the brain.
"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," per Nedergaard "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 researchers' findings build on the discovery that the brain has its own network of plumbing pipes i.e. the glymphatic system, which pumps cerebral spinal fluid (CSF) through the gaps around the brain cells. The toxins are flushed into the circulatory system and eventually make their way to the liver.
Scientists imaged the brains of mice and concluded that the glymphatic system is reportedly nearly 10 times more active when a person is sleeping rather then when awake.
However, per researchers the "true significance of the findings" and their impact can only be known after human studies are conducted.
"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," says Dr Raphaelle Winsky-Sommerer, a lecturer in sleep at Surrey University. "The significance is that, yet again, it shows sleep may contribute to the restoration of brain cell function and may have protective effects."
Disorders like Alzheimer's and Parkinson's are characterized by the build-up of toxins in the brain. With further insights into the brain's cleansing mechanism, a preventive solution for these ailments can perhaps be found in the future.
