Sleep deprivation stops brain cells communicating properly and affects how people see the world around them, a new study has shown.
The new research, which has serious implications for driving while tired, shows that parts of the brain actually turn themselves off to rest even though a person is still awake.
Brain scans of sleep deprived people by scientists at the University of California Los Angeles (UCLA) have shown for the first time that fatigue disrupts the speed the brain cells communicate and prevents memories being encoded properly. It also causes temporary lapses in memory and vision.
Dr Itzhak Fried, professor of neurosurgery at UCLA, said the effect could prevent a tired person noticing a pedestrian stepping in front of a car.
“Starving the body of sleep also robs neurons of the ability to function properly,” he said.
“This paves the way for cognitive lapses in how we perceive and react to the world around us. The very act of seeing the pedestrian slows down in the driver’s over-tired brain. It takes longer for his brain to register what he’s perceiving.
“Inadequate sleep exerts a similar influence on our brain as drinking too much. Yet no legal or medical standards exist for identifying over-tired drivers on the road the same way we target drunk drivers.”
For the research scientists studied 12 sleep-deprived epileptic patients who had electrodes implanted in their brains and were asked to categorise a variety of images as fast as possible.
Performing the task grew more challenging as the patients grew sleepier. And the scans showed that as the patients slowed down, their brain cells did, too.
“We were fascinated to observe how sleep deprivation dampened brain cell activity,” added lead author Dr Yuval Nir of Tel-Aviv University.
“Unlike the usual rapid reaction, the neurons responded slowly, fired more weakly and their transmissions dragged on longer than usual.”
In a second finding, the researchers discovered that in the areas where the cells were firing more slowly, brain waves also slowed down, suggesting the area was trying to sleep.
“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,” added Prof Fried.
Previous studies have tied sleep deprivation to a heightened risk of depression, obesity, diabetes, heart attacks and stroke.
The research was published in the journal Nature Communications.