Research conducted by scientists at the Massachusetts Institute of Technology in Boston has shed light on the changes that occur in the brain due to fatigue. According to the team’s findings, the loss of concentration in individuals suffering from sleep deprivation coincides with a surge of cerebrospinal fluid leaving the brain.
This process often hampers professional performance. For instance, during a business meeting, a sleep-deprived individual may find themselves unable to focus on a crucial issue right in the middle of the discussion. A typical outcome of such a “shutdown” is an accident caused by a drowsy driver.
And this is far from the only consequence of short-term lapses in attention, which is a common problem for those who regularly miss out on sleep. Scientists studied this phenomenon using electroencephalography (EEG) – a classic method for examining the bioelectrical activity of the brain. The team concluded that the attention deficits caused by sleep deprivation are a significantly more critical condition than they may seem.
How Does the Brain React to Sleep Deprivation?
“When a person’s attention wanes, a wave of fluid begins to pulse in the brain. It’s not just that your neurons are ignoring the world; significant changes in the composition of the fluid in the brain are also taking place,” said Dr. Laura Lewis, the lead author of the study.
The team involved 26 adult volunteers, as reported by The Guardian. Each participant underwent EEG scanning after a restful night of sleep and after being completely deprived of sleep. The researchers not only tracked the electrical activity of the brain but also analyzed physiological changes.
In the second phase of the study, participants were asked to complete specialized tests that measured their reaction times to specific signals. Unsurprisingly, after sleep deprivation, the volunteers showed significantly poorer results: they reacted more slowly or didn’t respond at all.
Lapses in attention were accompanied by striking changes. Scans revealed a wave of cerebrospinal fluid that was rapidly expelled from the brain after a lapse in attention and returned approximately one second after attention was regained. Such waves are typically observed during deep sleep and are believed to help the brain eliminate metabolic waste that accumulates throughout the day.
The researchers also observed that the participants’ pupils constricted about 12 seconds before the fluid left the brain and then returned to normal. Breathing and heart rates also slowed down, the researchers reported in the journal Nature Neuroscience.
The team says these disruptions happen when the brain tries to balance waking cognitive activity with functions it usually performs during sleep — in other words, the brain is trying to grab a quick rest.
Commenting on the work, neurobiologist Ria Kodosaki of University College London said these changes are probably “structured biological events typically observed at the onset of sleep, and lapses in attention are not passive but organized to give the brain a brief rest.”
She said the changes might be the brain’s way of protecting itself: they serve as “forced pauses” in which the brain temporarily disconnects from the external world to carry out important housekeeping tasks.
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