A new study delves into the human brain to see what makes us "spacey" after a poor night's sleep.
These findings could help explain why lack of sleep hinders a lot of mental functions, according to Itzhak Fried, rofessor of neurosurgery at the University of California, Los Angeles and author on the study. Fried explained that this is a reflection of how the brain reacts to different things and situations around us.
Fried and his colleagues observed 12 people preparing to receive surgery in UCLA to treat epilepsy. The patients had electrodes implanted in their brains in order to pinpoint the origin of their seizures prior to surgery.
The study claims that sleep deprivation is something that you can't catch up on, so for example, if you only get 4 hours one night, 12 hours the next night won't make up for the previous lack of 4 hours sleep.
During the study, 12 people were kept awake all night and then asked to categorise a variety of images as fast as possible.
"But it has been hard to determine precisely how sleep deprivation influences neural activity within the human brain owing to the invasive techniques required to record neural activity". Given its nature, the team focused on the temporal lobe. The research found that as they became sleepier, the task became increasingly hard.
As the patient's progress slowed down, so too did their neurons under the hood, the team reports.
What happened was that sleeplessness impacted how effectively neurons encoded regular information, and how visual stimuli were transposed into conscious perception.
"We were fascinated to observe how sleep deprivation dampened brain cell activity", said Tel Aviv University's Yuval Nir, the study's lead author. Neurons fired more weakly, Fried said, and communications lagged.
The same phenomenon can occur when a sleep-deprived driver notices a pedestrian stepping in front of his auto.
Scientists saw one more phenomenon alongside hampered brain activity: slower sleep-like brain waves, which Fried said suggest parts of a exhausted brain may rest even as other parts remain active. "It takes longer for his brain to register what he's perceiving", says Dr. Nir.
The researchers also discovered that slower brain waves accompanied sluggish cellular activity in the temporal lobe and other parts of the brain. These "sleep-like" waves heavily disrupted the patients' brain activity and ability to perform tasks. 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 effects are similar to "drinking too much". "Yet no legal or medical standards exist for identifying over-tired drivers the same way we target drunk drivers".