French researchers have discovered that it is possible to create new acoustic memories while one is asleep. The researchers were able to make 20 test subjects learn a complex pattern of sounds while asleep.
As reported in Nature Communications, the scientists played white noise (what one might call static) to the participants. Within these sequences of white noise, they created clips with 200-millisecond acoustic patterns embedded within, which they repeated five times. This approach was performed during REM, light non-REM, and deep non-REM sleep.
Upon waking up, the sleepers were asked to identify the pattern they listened to while asleep. If they listened to the audio clip during REM or light non-REM sleep, they were able to recall the pattern at better than random chance.
“The sleeping brain is including a lot of information that is happening outside,” lead author Thomas Andrillon told the Washington Post, “and processing it to quite an impressive degree of complexity.”
If this discovery wasn’t already enough, the team also found that the same approach during the deepest phases of non-REM sleep made people worse at remembering the pattern – a weird “anti-learning” phenomenon.
According to Andrillon, this research reconciles both sides of the debate regarding memories and sleep. Some researchers think that sleep strengthens memories that are played back, while others think that the brain purges some memories and leaves others intact. This study suggests that both might be happening, only at different times during the sleep cycle.
The research is clearly intriguing, but our understanding of the brain and its mechanisms remains extremely limited. Also, this shouldn’t be seen as a first step towards some magical sleep-learning machine that allows you to learn French while you sleep. This approach, formally known as hypnopedia, was disproved in the 1950s, although it remains popular.
The researchers weren’t able to assess if this sleep-learning approach had any other effect on normal sleeping functions. While we sleep, the brain’s glymphatic system is at its most active. This system allows the brain to clear itself of waste products from the molecular reaction inside its cells. Sleep-learning might be messing with this. It goes without saying that when it comes to our understanding of the brain, more research is necessary.
[H/T: Washington Post]