When you sleep, your brain undergoes a fascinating “detox” process that removes waste products linked to Alzheimer’s and dementia. In fact, this cleansing activity is 10 times more active during sleep than while awake.

Neuroscientist Jeffrey Iliff and his colleagues at the University of Rochester spent years trying to figure out how the brain rids itself of toxins produced as a byproduct of thought – since it’s not carried away by blood vessels. Their experiments on mice discovered that, during sleep, the brain showers itself with a cerebrospinal fluid.  Iliff said, “That continuous flow sweeps along particles that are sitting in between the cells.”
Brain Cells Shrink during Sleep
 

Using imaging technology known as two-photon microscopy, the researchers looked at the timing of this flushing process and discovered brain cells contract during sleep, expanding the areas between brain cells by as much as 60 percent. With brain cells smaller and the space between them larger, there’s more room for the cerebrospinal fluid to move freely.

Maiken Nedergaard, M.D., co-director of the Center for Translational Neuromedicine at University of Rochester Medical Center, compared the changes that occur during sleep to “turning on a faucet.” She added that sleep is necessary for this “active clearance of the by-products of neural activity” to take place.

Last year, Nedergaard and her team discovered a scrubbing process taking place around brain cells. In this year’s research, they discovered that not only does the “glymphatic system” kick into high gear only during sleep, but, during that time, it also mops up significantly more of the toxic protein amyloid-beta, considered a primary culprit in Alzheimer’s disease.

 
Important Clue in Preventing Alzheimer’s
 

The discovery of the brain’s nocturnal cleaning service, coupled with previous research out of Washington University showing that levels of beta-amyloid drop during sleep, could open up new avenues of prevention and treatment for Alzheimer’s and dementia. Previous research found that depriving mice of sleep led to accumulation of amyloid-beta protein.

“In Alzheimer’s disease, one of the things that happens is amyloid beta clogs up the space between the cells, and it’s thought that is what kills the neurons and causes the dementia that is the hallmark of Alzheimer’s disease,” said Professor Iliff.

Bottom line, sleep is both a physical and mental necessity. If you don’t sleep, the sewers back up, causing the toxic byproducts of thought to clog up your brain – leading to disease. Most people need between 7 and 9 hours of sleep each night.