Sleep Deprivation Disrupts Brain Activity as Much as Alcohol by Causing Mental Glitches and Lapses

After a really bad night's sleep, it can be difficult to function properly: you find yourself forgetting things, or exercising poor judgement.

Now a study by researchers from UCLA, the École Normale Supérieure in Paris, Tel Aviv University, Nanthia Suthana of UCLA and the University of Wisconsin, Madison, is helping to shed some light on why.

The research, promoted in a statement from UCLA and published in Nature Medicine, was based on a sample of 12 epilepsy patients. But despite the small size its authors believe it can tell us important details about the effect of sleep deprivation on the functioning of brain cells.

The 12 patients, who were set to have surgery at UCLA to treat their condition, had electrodes implanted in their brains aimed at seeking out the root of their seizures. People undergoing this procedure stay awake all night, as a lack of sleep can bring on epileptic attacks.

While awake, the subjects were asked to sort a variety of images in the shortest time they could. Across the participants, the electrodes recorded almost 1,500 brain cells firing as they carried out the task.

Performing the task was more difficult the more tired the patients became, and their brain cells slowed accordingly.

"We were fascinated to observe how sleep deprivation dampened brain cell activity," said Yuval Nir of Tel Aviv University.

"Unlike the usual rapid reaction, the neurons responded slowly and fired more weakly, and their transmissions dragged on longer than usual."

"Slow, sleep-like waves disrupted the patients' brain activity and performance of tasks," UCLA's Dr. Itzhak Fried said.

"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."

And, the authors said, it might be time for a rethink on how we view sleep deprivation, which can have a similar effect on the brain to alcohol intoxication.

"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."

The team plans further tests, including some that dig in more detail into the benefits of sleep.