Learning while sleeping

Sleeping book womanWoman sleeping on a pile of books. Photo: Thư Anh / Unsplash

Is it possible to learn a language while sleeping?

Researchers have finally proven that we can acquire vocabulary from a totally unknown language while we are in deep sleep. Even more important – they remain stored in memory after we wake up.

The time in «Never, Never Land» has been viewed as little productive. One question has been central to sleep research: Can you use the dream time to learn, a totally unknown language, or similar? Several sleep scientists have previously doubted that. An interdisciplinary team at the University of Bern in Switzerland believes that it is possible.


Test persons who slept during daytime learned a selection of words. The words represented large and small objects such as houses, elephants, key and cork. They were constructed from a fictitious language with corresponding translations.

The words were read out loud to the “lab rats” several times. During specific stages of deep sleep, memory formations appeared in the hippocampus. The hippocampus is likely the most important memory bank of the brain.

After they were awakened, the persons had the words read back to them while being awake. They largely managed to place them into different categories by size.

The test subjects, in other words, managed to recall from memory associations to several words in a completely unknown language. Words which they have no prior knowledge of before they had a cat nap earlier in the day.

Both exciting and important

Professor at the Department of Psychology at the University of Bern, Katharina Henke, has led the research collaboration «Decoding Sleep» alongside Marc Züst and Simon Ruch.

Henke predicts that research on how to benefit from deep sleep learning will be a topic in the years to come. It will also be a topic that will have the potential to add information to the brain in an unconscious state.

Sleep researcher, Bjørn Bjorvatn, is the leader and professor at the National Center for Competence in Sleep Disorders at Haukeland University Hospital in Bergen.

“These are exciting results, which again show that sleep is very important. Here the research demonstrates its importance for memory and learning. Several other studies have shown the importance of sleep for a number of different functions as well,” he tells NTB.

Same brain area

The results of the study are published in the research journal «Current Biology». Co-author, Marc Züst, finds it particularly interesting that when the test subjects were to associate something with the foreign-language words, the memories were extracted from the same area of the brain that stores memories from normal learning – namely, the hippocampus.

These brain constructs seem to shape memories, regardless of the state of consciousness – unconsciously under deep sleep or conscious while awake, Züst explains.

One of the other researchers behind the project, Simon Ruch, believes the results demonstrate that even advanced learning is possible during deep sleep.

Long way to go

It is a long way to traverse before you can possibly assume the horizontal position and learn a language fluently while sleeping.

Bjorvatn reminds that you, nonetheless, should take into account that the research once again shows the importance of sleep in order for the body to function.

“Think about how many persons don’t prioritise sleeping high enough. That has consequences. Perhaps something to think about when, in the evening, one chooses to stay awake for one hour more – instead of prioritising sleep,” he lectures NTB.

Facts about sleep

  • A condition where the body is in deep rest, energy consumption is reduced and body movements and intellectual functions reduced.
  • Due to reduced physical and mental capacity, one will to a lesser extent react to sensory stimuli such as sounds, light and touch.
  • Reaction to sensory stimuli depends on how deep sleep is, how strong the stimuli one is exposed to and whether they are smooth or sudden.
  • Sleep is often divided into five stages where synchronized sleep, without eye movements and dreams, constitutes the first four and dream sleep, the so-called REM sleep, the latter. The stages are repeated several times throughout the night.
  • The dream sleep amounts to about 20 per cent of a normal night’s sleep for adults.
  • About one-third of human life is used for sleep, and no one really knows why it is necessary.
  • It is quite clear that adequate sleep can be an important factor for, among other things, feeling well-being, for emotional balance, for better tolerating various stresses and pain and for concentration ability. How sleep really contributes is not certain.
  • According to some theories, sleep is necessary to further develop impressions from the awake state. Processing of today’s experiences, sorting information, storing information in the memory and forming new compounds in the brain may need to happen undisturbed and at rest.
  • Scientists have long asked the question whether the brain can be filled with knowledge and learn things while sleeping, which can later be taken advantage of.

Facts on learning in your sleep

  • Over the past 20 years, it has been proven several times that humans can absorb new information while they are sleeping, but it remains to be proven that it is possible to learn something advanced and take advantage of it in the waking state.
  • In 2019, Swiss scientists have for the first time shown that linguistic information, in the form of words in a foreign language with related translations, can be stored in memory during deep sleep where brain waves are slow and when the brain is in active mode. They also showed that associations with the words can be retrieved from the memory in the awake state.
  • The 75 German-speaking persons, who participated in the experiment, did not know what to test for, only that they should be researched while they were sleeping. Only 41 of them reached as deep sleep as needed for the slow wavelengths of the brain to appear and a memory to be formed.
  • 40 fictitious words with German translation were read out for them four times. For example, the German word for “house” was translated into the fictional word “tofer”, the word “cork” was “aryl”, “elephant” was “guga”. When they woke up, the fictitious words were read out. The test subjects were then asked whether this was an object that would fit in a shoebox or not.
  • Even during deep sleep, the brain switches between active and inactive mode every half second. The results show that the chance that the test persons got the correct answer to the test when they were awake, increased with the number of times they had been reading words while the brain was in active mode during deep sleep.


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