The brain is still active during sleep

Contrary to popular belief that the mind rests while we are sleeping, new research suggests that the brain is highly active when our eyes are closed – and can even classify words.

In the journal Current Biology, researchers from Cambridge and Paris have published a study which compared the brain’s behaviour in participants when they were awake and asleep.

When awake, the participants were asked to complete a word test, during which their brain activity was recorded via an electroencephalogram (EEG).

For the test, they were required to classify spoken words as either objects or animals by pressing a button in their left or right hand.

Next the participants had to lie in a darkened room with their eyes closed while continuing the word classification task in their head.

After they had drifted off to sleep – and were completely unaware and motionless – scientists tested the participants with a new set of words. This was to ensure the brain had to figure out the meaning of the words before classifying them using the buttons.

The recorded brain activity was shown to be just as accurate as it had been while the participants were awake – albeit a little slower.

Sid Kouider, from the Ecole Normale Superieure in Paris claims any task that can become automated can be maintained during sleep. This, he explains is why we are sensitive to naming in our sleep and responding to specific sounds such as our alarm clocks.

This research could pave the way for future studies on the processing capacity of our brains while we are sleeping.

“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,” Mr Kouider said.