Sleep learning is real, scientists say, as they show the brain’s ability to form new memories

A sleeping brain can form fresh memories, according to a team of neuroscientists. The researchers played complex sounds to people while they were sleeping, and afterward the sleepers could recognise those sounds when they were awake.

The idea that humans can learn while asleep, a concept sometimes called hypnopedia, has a long and odd history. It hit a particularly strange note in 1927, when New York inventor A. B. Saliger debuted the Psycho-phone. He billed the device as an “automatic suggestion machine”. The Psycho-phone was a phonograph connected to a clock. It played wax cylinder records, which Saliger made and sold. The records had names like “Life Extension”, “Normal Weight” or “Mating”. That last one went: “I desire a mate. I radiate love ... My conversation is interesting. My company is delightful. I have a strong sex appeal.”

Thousands of sleepers bought the devices, Saliger told The New Yorker in 1933. (Despite his enthusiasm for the machine – Saliger himself dozed off to “Inspiration” and “Health” – the device was a bust.

But the idea that we can learn while unconscious holds more merit than gizmos named Psycho-phone suggest. In the new study, published Tuesday in the journal Nature Communications, neuroscientists have finally showed that it is possible to learn while sleeping.

“We proved that you can learn during sleep, which has been a topic debated for years,” said Thomas Andrillon, an author of the study and a neuroscientist at PSL Research University in Paris. Just don’t expect Andrillon’s experiments to make anyone fluent in French.

Researchers in the 1950s dismantled hypnopedia’s more outlandish claims. Sleepers cannot wake up with brains filled with new meaning or facts, Rand Corp researchers reported in 1956.

Yet success is possible, if you’re not trying to learn dictionary definitions or kung fu. In recent years, scientists have trained sleepers to make subconscious associations. In a 2014 study, Israeli neuroscientists had 66 people smell cigarette smoke coupled with foul odours while they were asleep. The test subjects avoided smoking for two weeks after the experiment.