Can you learn a language while sleeping?

In the classic sci-fi action movie, Matrix, Neo, played by Keanu Reeves, learns all the martial arts of the world by downloading it into his brain while he sleeps. So wouldn’t it be cool if you could just fall asleep and learn the language you’ve been working on while you dream? Well, now you can. And, to be honest, you always could.

To say that we learn languages while we sleep is technically true, in that our brain consolidates language learning processes while we sleep. However, to say that we can passively learn languages by listening to an audio recording in the target language while sleeping is only partially true, and that also only in a technical manner. Studies have shown that cueing certain words during sleep, that is, words that were learnt during wakefulness, can have a beneficial effect on subsequent recall. However, note that this refers to words that have been learnt before sleep. You will not be acquiring new words like Neo acquired new kung-fu moves while sleeping.

Generally speaking the more you use a language the stronger the neural paths become, the faster the information is communicated within the brain and the more immediate your recall. This is no simple task because the matching and wiring that must be performed covers disparate domains like phonetics, syntax, comprehension, motor control (that is, the delicate coordination of the muscle movements of the tongue, palate and vocal chords), and all the rest of what communication involves. That’s why the brain does much of this back office organisational activity for sleep, although the strengthening of memory associated with language learning occurs in both wakefulness and sleep. The question is, is it possible to actively learn during sleep by listening to audio recordings and what is the optimum number of hours one should sleep to improve one’s language learning capacity?

Audio during sleep may backfire.

Listening to new material while sleeping has no effect on their recall later. It ma, however, lead to poorer quality sleep which may disturb the ability to memorise content learned while awake. In fact, a recent study revealed that cuing words during sleep had two potential effects. For those who spent more time in rapid-eye-movement sleep cycle during sleep while the audio was played, they were able to remember those words better. However, for those who spent more time in the slow-wave sleep cycle, their memory of the cued words were worse than words that were not cued during sleep. This suggests that listening to words during the slow-wave sleep cycle may make disrupt or disorganise the connections associated with that word. The researchers theorise that slow-wave sleep may be responsible for consolidating memory and that being exposed to an auditory cue during that sensitive time may destabilise a new memory and contaminate it by connecting it with unassociated information.

When considering how long one should sleep to ensure best language learning outcomes, we should note that both rapid-eye-movement sleep (REM) and slow-wave sleep (SWS) are vital to memory associated with language acquisition. The brain is constantly seeking to balance stability and openness to new infromation, also known as plasticity. We can conceive of SWS as time for allowing modification of existing memory. It allows new memory to get associated with other information. REM then consolidates this memory and integrates it with long-term memory.

Since both REM and SWS are considered deeper sleep stages, one would do best for their language learning endeavours by establishing good sleep habits. It takes between 10 minutes to 40 minutes to enter into SWS sleep, and it may take up to 90 minutes to have prolonged periods of REM sleep. Anyone trying to learn a language and trying alternative sleep cycles may not be doing their langauge learning a service, although if there is a way to hack the system to optimise the ratio of SWS and REM for learning, please share your insights in the comments.

When I started learning Italian I noticed that instead of saying “ora” or “adesso”, which is Italian for “now”, I would repeatedly say “ima” (今) which is its translation in Japanese. I had stopped learning Japanese more than 10 years before, but my brain had softcoded ima with the notion of how-to-say-now-in-a-foreign-language. In order to disassociate this, I had to practise Italian for quite a lot longer, and I imagine sleep had a lot to do this process. If you’ve been noticing you are not learning as well as you’d like, perhaps you are not getting enough sleep to allow for new memory formation. Ensure you sleep well and enjoy the journey to long-term fluency.