A new study delves into the human brain to see what makes us 'spacey' after a poor night's sleep.
Ever had a particularly poor night of sleeping that just ruins your next day? I certainly did, and it's currently a running gag among my friends that I won't drive unless I've had my 'beauty sleep'.
Science, as ever, comes to save my honor -- this time, with a study looking into the effects of sleep deprivation on the brain. Authored by researchers from the US and Israel, the paper reports that poor sleep will disrupt neurons' ability to communicate with each other, creating temporary mental lapses that negatively impact memory capacity and visual perception.
"We discovered that starving the body of sleep also robs neurons of the ability to function properly," said senior author Dr. Itzhak Fried, professor of neurosurgery at the David Geffen School of Medicine at UCLA and Tel Aviv University. "This paves the way for cognitive lapses in how we perceive and react to the world around us."
Fried led his international team of researchers while studying 12 UCLA epileptic patients. The patients had electrodes implanted in their brains prior to surgery in order to pinpoint the origin of their seizures. As a lack of sleep has been linked to an increased incidence of seizures, the patients stood awake during the night to try and cause an epileptic episode and shorten their stay in the hospital.
Sleep not, process not
The team asked these patients to categorize a number of images as fast as they could. The electrodes were used to record the activity of some 1,500 of their neurons in real time while they went about the task. Given its nature, the team focused on the temporal lobe. This area of the brain regulates visual perception and memory. Outwardly, the team could tell right away that the sleepier the participants got, the harder it was for them to perform the sorting task.
As the patient's progress slowed down, so too did their neurons under the hood, the team reports. Sleep deprivation interfered with the neurons' ability to process information, encode it, and then translate the visual stimulus into conscious thought.
"We were fascinated to observe how sleep deprivation dampened brain cell activity," said 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."
Dr. Nir says that this same phenomenon can make a sleepy driver sluggish in reacting to a stimulus -- such as a pedestrian stepping in front of the car.
"The very act of seeing the pedestrian slows down in the driver's over-tired brain," he explained. "It takes longer for his brain to register what he's perceiving."
The team further reports that this sluggish neuronal activity was also accompanied by slower brain wave patterns in the same region of the brain. These "sleep-like" waves heavily disrupted the patients' brain activity and ability to perform tasks. Fried says this suggests that certain regions of the brain were "dozing, causing mental lapses" while the rest was trying to stay awake and run as usual. The effects are similar to "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," he adds.
If you ever find yourself in this situation, there is some evidence that taking a quick nap will take the edge off of sleep deprivation.
The team plans to explore the benefits of a good night's sleep in more detail in the future and to uncover the mechanism responsible for the neuronal glitches that generate mental lapses.
The paper "Selective neuronal lapses precede human cognitive lapses following sleep deprivation" has been published in the journal Nature.