"You can imagine driving a car and suddenly somebody jumps in front of the car at night," Fried explained to NPR.
"If you are sleep-deprived, your cells are going to react in a different way than in your normal state," he added.
How was the study conducted?
Fried's research, which was published this week in the journal Nature Medicine, recorded data directly from the neurons of 12 epilepsy patients preparing to have surgery at UCLA.
Each patient had electrodes implanted into his or her brain, with the aim of locating the exact origin of their seizures before the procedure. The patients were then kept awake all night, as lack of sleep can provoke seizures.
After they were deprived of sleep, the patients were asked by researchers to quickly categorize a series of images. As they grew sleepier, the task became gradually more and more challenging, showing that their brains slowed down, just as they did physically.
"Unlike the usual rapid reaction, the neurons responded slowly and fired more weakly, and their transmissions dragged on longer than usual," Yuval Nir, the study's lead author from Tel Aviv University, said. Nir also said that the team was "fascinated" to see how sleep deprivation slowed down brain cell activity.
Lack of sleep slows down our ability to process information
According to the study's results, a lack of sleep directly affects the neurons' ability to translate visual input into conscious thought and encode information.
Some areas of the brain even fall asleep, while others struggle to remain awake. Essentially, when you haven't slept enough, your brain works more inefficiently and much slower.
Fried explained that his research also adds to a growing body of evidence demonstrating that you shouldn't drive when you're sleepy. More than 70,000 crashes per year are caused by drowsy driving, according to the Centers for Disease Control and Prevention.
"Severe fatigue exerts a similar influence on the brain to drinking too much," Fried said. "Yet no legal or medical standards exist for identifying overtired drivers on the road the same way we target drunk drivers."
On a more personal level, Fried said that doctors, nurses and medical students also should take note of the study. He pointed out that he worked exceptionally long hours during his neurosurgery residency. Previous research has also shown that medical students working long hours are more prone to make errors.
"I am trying to impose the lesson I learned from my research on myself," Fried said.