Trying to concentrate? Maybe your brain is being washed
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We all know that it can be difficult to concentrate when you are sleep deprived, but why does this happen? This may be because your brain is trying to refresh itself, leading to short-term lapses in attention.
During sleep, the brain performs a flushing cycle that clears the cerebrospinal fluid (CSF). repeatedly enters the organ and exits again at the base of the brain. This process clears metabolic waste accumulated throughout the day, which could otherwise damage brain cells.
Laura Lewis from MIT and her colleagues wondered whether the loss of attention that typically occurs after sleep deprivation might be the result of the brain trying to catch up on brainwashing while it's awake.
To study this idea, the researchers asked 26 people between the ages of 19 and 40 to get a good night's sleep so they felt well-rested, and then kept them up all night in a laboratory two weeks later.
In both cases, the team recorded participants' brain activity using fMRI the next morning while they completed two tasks. During these tests, participants had to press a button whenever they heard a certain signal or saw a cross on the screen turn into a square. This happened dozens of times in 12 minutes.
As expected, participants did not press the button significantly more often when they were sleep deprived compared to those who were well rested, meaning that lack of sleep made it more difficult to concentrate.
Importantly, when the researchers analyzed the brain scans, they found that the participants lost concentration about 2 seconds before the cerebrospinal fluid was flushed from the base of the brain. Moreover, cerebrospinal fluid returned to the brain approximately 1 second after attention was restored.
“If you think of the brain cleansing process as a washing machine, you kind of have to pour the water in, then splash it out, and then drain it, and so we talk about the splashing happening during these lapses of attention,” Lewis says.
The results show that when the brain can't clear itself during sleep, it does so while you're awake, but this impairs concentration, Lewis says. “If you don't have these waves [of fluid flowing] at night because you're up all night, then your brain starts to sort of pick them up during the daytime, but they require such a price of attention.”
“Exactly why this clearing process leads to loss of attention remains unclear, but identifying the brain regions responsible may help find ways to reduce the cognitive effects of sleep deprivation,” Lewis says.
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