Brain Flushes Fluid During Attention Gaps Caused by Lack of Sleep
- MM24 News Desk
- Nov 2
- 3 min read
MIT scientists have uncovered a striking link between sleep deprivation and attention lapses: waves of cerebrospinal fluid (CSF) rush out of the brain at moments when focus fails, a process normally reserved for sleep. Led by Laura Lewis, the Athinoula A. Martinos Associate Professor of Electrical Engineering and Computer Science at MIT, the team shows that the brain’s attempt to catch up on its nightly “cleanse” comes at the cost of alertness.
In our fast-paced lives, few things are more familiar than dragging through a day after a restless night. Coffee only helps so much, and for many, the mind simply drifts. But until now, scientists have only had hypotheses about what was happening inside the brain during these fleeting lapses of attention. According to MIT, the answer lies in the same system that keeps the brain clean during sleep: cerebrospinal fluid, the clear liquid that cushions the brain and removes metabolic waste.
“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 Professor Laura Lewis, who is also a member of MIT’s Institute for Medical Engineering and Science, the Research Laboratory of Electronics, and an associate member of the Picower Institute for Learning and Memory. This groundbreaking insight is detailed in a study published in Nature Neuroscience, with Zinong Yang, a visiting MIT graduate student, as the lead author.
To explore how these CSF pulses relate to attention, the researchers recruited 26 volunteers, testing each under conditions of both sleep deprivation and normal rest. Using a combination of electroencephalogram (EEG) caps and functional magnetic resonance imaging (fMRI), the team measured brain waves alongside CSF flow, heart rate, breathing, and pupil size while participants completed visual and auditory attention tasks. Participants were asked to respond to changes in a screen or beeps, and the difference in performance between well-rested and sleep-deprived participants was dramatic. Sleep-deprived subjects missed more stimuli and had slower reaction times, correlating with the moments when CSF flowed outward from the brain, according to MIT reporting.
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“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,” Professor Lewis explains. The study suggests that when the brain lacks sleep, it triggers CSF pulses to compensate for lost cleansing, but these pulses disrupt attention in real time. Yang adds, “Your brain’s fluid system is trying to restore function by pushing the brain to iterate between high-attention and high-flow states.”
Interestingly, the team also observed body-wide changes accompanying these lapses. Pupil constriction began approximately 12 seconds before the CSF outflow, and heart rate and breathing slowed concurrently. “It seems like there’s a unified circuit controlling both attention and basic physiological processes,” says Professor Lewis. Though the exact neural circuit remains unidentified, the noradrenergic system, which regulates brain and body functions via norepinephrine, is a likely candidate.
These findings underscore why sleep matters beyond feeling refreshed—it’s not just rest for the mind, but a vital cleansing process that preserves attention, cognitive function, and even bodily regulation. According to MIT, the study bridges a gap between our understanding of physiological maintenance during sleep and the moment-to-moment lapses in attention that accompany deprivation.
Funded by the National Institutes of Health and multiple fellowships including the Sloan and McKnight Scholar Awards, this research opens doors for exploring interventions to mitigate attention lapses in sleep-deprived individuals, from students to shift workers, and even pilots and medical professionals.
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