A child dreams of Santa Claus. (CC/Howcheng)
PARIS, Sept. 12 (UPI) -- The brain is active during sleep -- that much was already obvious. We dream in our sleep, talk in our sleep, even swat away tickling feathers in our sleep. But now a new study shows the brain can even perform seemingly complex processes -- like classifying a word as real or nonsense -- while asleep.
Researchers at the Ecole Normale Supérieure in Paris recently teamed up with scientists at the University of Cambridge to study the processing capacity of sleeping brains. The researchers used a simple word test, having participants use a hand signal device to categorize the given word as being either an animal or an object.
By attaching each participant to an EEG and recording neural impulses, researchers were able to tell when the word game had become automatic. Once the word-categorization process had become automatized by the brain, researchers had the participants perform the same test -- only using different words -- in a reclined chair in a dark room. They found that the participants performance did not decline has each one drifted off to sleep.
"We show that the sleeping brain can be far more 'active' in sleep than one would think," explained Sid Kouider of Ecole Normale Supérieure. "Far from falling [into] a limbo when we fall asleep, parts of our brain can routinely process what is going on in our surroundings and apply a relevant scheme of response. This explains some everyday life experiences such as our sensitivity to our name in our sleep, or to the specific sound of our alarm clock, compared to equally loud but less relevant sounds."
Kouider says he believes processing capacity of a sleeping brain is limited by the complexity of the given task, so long as the task can be automated. Researchers hope to do further testing to find out what their discovery might say about the ability to learn while sleeping. Though Kouider acknowledges interrupting sleep in any way, even if we're not aware of the interruption, could potentially have health ramifications.
"Research focusing on how to take advantage of our sleeping time must consider what is the associated cost, if any, and whether it is worth it," Kouider said.
The research of Kouider and his colleagues was published in the journal Current Biology this week.
