It’s known that our brains can review what we’ve learned during the day increasing the chances of retention. A recent study also suggested that the brain retains best what we most desire to learn.
However, it’s never been clear that something new going on during sleep can be accessed by our brains. Now, a team of neuroscientists played complex sounds to people while they were sleeping, and afterward the sleepers could recognize those sounds. Such learning has been a debated topic for years according to one author of the study1.
Researchers in the 1950s dismantled claims that sleepers can learn facts, so you can’t learn a new language or concrete subject matter by playing DVDs while you sleep. Don’t bother putting a book under your pillow. However, it seems that the sleeping brain can take in some sensory information and store it in the subconscious. This is only possible during REM sleep according to the team. In a 2014 study, Israeli neuroscientists had 66 people smell cigarette smoke coupled with foul odors while they were asleep. The test subjects avoided smoking for two weeks after the experiment.
Maybe we can learn to break bad habits during sleep. Hmm, if there are smells associated with projects we want to complete, we could combine those smells with the smell of fresh-baked bread or lilacs while we doze the night away.
I assume—correctly—that the sleeping brain cannot tune into visual cues. I wonder if touch has been studied. Might wake us up and I can’t think of a useful experiment or application.
It seems to me the practical implications are minimal, but I find the fact that our brains are not completely out of it during sleep is fascinating and adds to our understanding of how that 3 pounds of matter works.
1, Thomas Andrillon, a neuroscientist at PSL Research University in Paris
PS: Still in Eastern Europe and the farewell dinner is on our anniversary.