A French research has shown through new video evidence that humans are able to repeat learned patterns of behaviour even while asleep.
Researchers at France's Universite Pierre et Marie Curie-Paris devised a simple test to explore the brain's potential while the body is at rest.
According to Wired, the team, led by Delphine Oudiette, taught a motor task to people with sleep behaviour disorders, those who typically move their bodies in tandem with dreams.
Their belief was that the test subjects might repeat the task while sleeping, providing evidence of what sleep researchers call "replay".
"Replay" is the hypothesis that the brain "replays" the actions of the day while we sleep.
It had traditionally been thought that the brain was a blank canvas for neurological activity in that period, because people tend to better remember facts after a good night's sleep, rather than when more tired.
However, evidence has increasingly shown that brain activity during sleep is very similar to its activity while learning.
Oudiette's team took on that grey area, asking subjects to hit a series of coloured buttons when shown the corresponding colours on a TV monitor.
They were then asked to simulate the task while lying - awake - in bed.
Further, they were videoed while asleep and the results showed in many instances that their movements during sleep mimicked their movements during the test.
"To our knowledge, the present findings represent the first direct and unambiguous demonstration of overt behavioural replay of a recently learned skill during human sleep," the Daily Mail quoted the researchers as writing.
The findings, reported in Public Library of Science ONE, could provide "highly valuable information about cognitive and motor processes occurring during sleep".