A new study is shedding light on the process that occurs in our brain when we ‘zone out’ due to a lack of sleep.
According to researchers, during brief lapses in focus, a wave of cerebrospinal fluid (CSF) flows out of the brain — the same process that typically occurs when we sleep, helping to remove waste that can accumulate during the day.
Researchers theorize that when a person is sleep-deprived, the body tries to catch up on the cleaning process by kick-starting the CSF flow during waking hours. However, the process typically results in brief impairment of attention.
“If you don’t sleep, the CSF waves start to intrude into wakefulness where normally you wouldn’t see them. However, they come with an attentional tradeoff, where attention fails during the moments that you have this wave of fluid flow,” says senior author Laura Lewis, the Athinoula A. Martinos associate professor of Electrical Engineering and Computer Science, a member of MIT’s Institute for Medical Engineering and Science and the Research Laboratory of Electronics, and an associate member of the Picower Institute for Learning and Memory, per Neuroscience News.
Lewis and her colleagues gathered over two dozen volunteers to study the different impact on the brain between having a restful night of sleep and a night without sufficient shut-eye. Sleep-deprived participants were found to perform significantly worse than well-rested peers on two different attentional tasks.
Not only were response times slower, but some participants failed to register brainwave changes in response to certain stimuli, suggesting momentary lapses of attention. It was during these brief periods that the researchers identified a flux of CSF out of the brain.
“The results are suggesting that at the moment that attention fails, this fluid is actually being expelled outward away from the brain. And when attention recovers, it’s drawn back in,” Lewis says.
Zinong Yang, lead author of the paper and MIT postdoctoral associate, says the brain is so desperate for sleep that it attempts “to enter into a sleep-like state to restore some cognitive functions.”
“Your brain’s fluid system is trying to restore function by pushing the brain to iterate between high-attention and high-flow states.”