Sleeplessness slows down our brains, which affects how we perceive stimuli. This may put us in dangerous situations.
Lately, many studies have focused on how sleep affects the ways in which our bodies function, and especially on how it impacts the brain.
New research from the David Geffen School of Medicine at the University of Los Angeles, California (UCLA) and Tel Aviv University in Israel now confirms that sleep-deprived people experience memory lapses and may deal with distorted visual perception; the communication between neurons is temporarily impaired.
"We discovered that starving the body of sleep also robs neurons of the ability to function properly. This paves the way for cognitive lapses in how we perceive and react to the world around us."
Senior study author Dr. Itzhak Fried
The results of the study were published in the journal Nature Medicine.
'Sluggish' neurons communicate inefficiently
The researchers worked with 12 people with epilepsy, who were also registered as patients with UCLA. The participants all had electrode implants in their brains, with the purpose of registering where their seizures originate in the lead-up to surgery.
As part of their assessment, seizures were induced by sleeplessness: participants were kept awake through the night until they experienced a seizure, so the electrical activity in the brain could be duly monitored.
In the experiment, participants were given a categorization task in which they had to sort different images into categories as quickly as possible.
While they performed this task, the researchers focused on the electrical activity in the temporal lobe of the brain, which has been associated with memory and visual recognition.
The scientists noticed that the sleepier and more tired the participants became, the more difficult they found the task, and the slower they performed.
"We were fascinated to observe how sleep deprivation dampened brain cell activity," explains lead study author Dr. Yuval Nir. He notes that with lack of sleep, brain cells became "sluggish" and neural communication was impaired.
"Unlike the usual rapid reaction," he says, "the neurons responded slowly, fired more weakly, and their transmissions dragged on longer than usual."
What happened was that sleeplessness impacted how effectively neurons encoded regular information, and how visual stimuli were transposed into conscious perception.
Activity in overtired brains is 'sleepy'
The scientists cited some existing research that detailed some potentially catastrophic effects of sleep deprivation. When drivers are tired, for example, their attention wanders because the neurons aren't responding as efficiently as they should.
"The very act of seeing the pedestrian slows down in the driver's overtired brain. It takes longer for his brain to register what he's perceiving," says Dr. Nir.
It was also found that brain cells that took longer to respond were associated with slower brain waves — such as those normally registered during sleep phases — and that this slow-motion activity was located in the same brain regions.
"Slow sleep-like waves disrupted the patients' brain activity and performance of tasks," explains Dr. Fried. "This phenomenon suggests that select regions of the patients' brains were dozing, causing mental lapses, while the rest of the brain was awake and running as usual."
The researchers insist that sleep deprivation should be taken much more seriously than it currently is, given its real dangers. Dr. Fried even goes as far as to compare lack of sleep with overdrinking, and to suggest that more adequate actions should be taken against tired driving.
"Inadequate sleep exerts a similar influence on our brain as drinking too much," says Dr. Fried. "Yet no legal or medical standards exist for identifying overtired drivers on the road the same way we target drunk drivers."
The scientists note that future studies should aim to target the brain mechanisms responsible for memory and perception lapses, as well as foreground the benefits of a good night's sleep.