New study finds it's possible to learn a different language in your sleep

Remember those school days where you would sit at home agonising over your French homework, just wishing there was an easier way to memorise all those new words? There are so many things that all of us tried in order to cram all that new vocabulary into our heads: post-it notes, flash cards, endless repetitions of the same "j'aime aller à la piscine" - it all just blurred into one wordy mess in the end.

At some point along the way, you may have heard someone - jokingly - tell you to sleep with your textbook under your pillow. That way, you'd "absorb" the language in your sleep.

Of course, that idea is ridiculous... but not completely impossible.

As some Swiss researchers have recently discovered, there is actually a way of teaching people a new language in their sleep. However, it's a little more sophisticated than simply sleeping on a book.

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The team, led by Katharina Henke, Marc Züst, and Simon Ruch from the Bern Institute of Psychology, theorised that they could teach people new words by playing them while a subject was asleep. And they were correct! ... Sort of!

According to a summary of the study published in Current Biology, "Sleep-formed associations translated into awake ones" amongst the subjects of the test. In other words, things told to the volunteers while they were taking a nap had been stored in their brain in some capacity and could be accessed when they were awake.

However, it wasn't as if volunteers for the study came away speaking fluent French/Spanish/Klingon after one nap with a pair of headphones on.

In a paper published on the study, the researchers explained that what we understand about the way the sleeping brain functions is still fairly limited, and so it is impossible to fully understand how the brain learns while it is not fully conscious.

"Learning while asleep is a dream of mankind, but is often deemed impossible because sleep lacks the conscious awareness and neurochemical milieu thought to be necessary for learning," they said. "Current evidence for sleep learning in humans is inconclusive."

Still, that did not stop them from going ahead with the tests.

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"To explore conditions under which verbal learning might occur, we hypothesized that peaks of slow waves would be conducive to verbal learning because the peaks define periods of neural excitability," they said.

Then, they went on to explain how exactly they set about teaching people a new (made up) language:

"While in slow-wave sleep during a nap, a series of word pairs comprising pseudowords, e.g., “tofer,” and actual German words, e.g., “Haus” (house), were played to young German-speaking women and men. When the presentation of the second word of a pair (e.g., “Haus” of “tofer-house”) coincided with an ongoing slow-wave peak, the chances increased that a new semantic association between the pair had been formed and retained.

"Sleep-formed associations translated into awake ones, where they guided forced choices on an implicit memory test. Reactivations of sleep-formed associations were mirrored by brain activation increases measured with fMRI in cortical language areas and the hippocampus, a brain structure critical for relational binding. We infer that implicit relational binding had occurred during peaks of slow oscillations, recruiting a hippocampal-neocortical network comparable to vocabulary learning in the waking state."

Basically, the scientists were able to teach people new words during a certain period of sleep, and - though the test subjects could not recall the exact definition of a word when awake - individuals involved in the experiment demonstrated that they were able to learn even when their brains were not fully conscious.

So, while we're not yet at the stage where we can take a powernap and wake up multi-lingual, we have discovered the basis for sleep-based learning, and that's an incredibly exciting prospect.