SCIENCE

Image by Gregory Pappas

The brain wash

Scientists may have discovered what it is about sleep that proves so beneficial for our brains. Apparently, as we slumber, our brain is rinsed by cerebrospinal fluid (CSF). Studying 13 healthy, young people using an MRI scanner as they slept, researchers monitored different sorts of brain activity, including CSF movement. 

The MRI exposed waves of fresh CSF flowing into the sleeping brains. A pattern quickly revealed itself: the CSF streamed into the brain at 20-second intervals. “I’ve never had something jump out at me to this degree,” said study co-author Laura Lewis, a neuroscientist and engineer at Boston University. “It was very striking.” While small, gentle waves of CSF occur when we’re awake, the sleep waves were, by comparison, tsunamis. “The waves we saw during sleep were much, much larger, and [of a] higher velocity,” she said.

Responding to the results, Maiken Nedergaard, a neuroscientist at the University of Rochester Medical Centre in New York, said the study “elegantly links a number of seemingly unrelated topics in neuroscience, including sleep, brain waves, cerebrospinal fluid flow and blood flow, together.”

The findings have given Nedergaard and others good reason to conduct more research into CSF. In particular, to determine whether the fluid may also clean the brain from proteins associated with Alzheimer’s disease. Just that possibility alone, said Nedergaard, makes the CSF findings “a significant move”. 

November 3, 2019

Blood flows out of and cerebrospinal fluid flows into the sleeping brain