- It is possible to learn new vocabulary during deep sleep
- New foreign words and translated words, when played during deep sleep can become associated and last until waking
- Recalling the words correctly after waking, proves that sleep-learning is a reality
Sleeping is very important for maintaining a healthy body and mind. It is well established that the information learned during wakefulness is stabilized and consolidated during sleep and stored as memory.
The memory traces can be further strengthened if the already learned information is re-played during deep sleep. This is possible because the brain can re-process the information over-and-over again to consolidate the memory. However, it is not known if the brain can process new information that is input during sleep, such as learning new words and recalling them after waking.
It is hypothesized that if re-playing learned information during sleep can facilitate the brain to consolidate memory; it could also be possible for the brain to learn new information played for the first time during sleep. In fact, this hypothesis has been proved by the unprecedented findings of this study.
The study has been published in the journal Current Biology, a Cell Press publication.
Key Aspects of the StudyThe primary aspects that were investigated pertain to brain activity and its role in language processing. These are briefly highlighted below:
- Brain activity fluctuates between active states ("Up-states") and inactive states ("Down-states") during deep sleep
- Duration of active ("Up") and inactive ("Down") states lasts for half-a-second each
- Semantic associations between foreign words and translated words during deep sleep were evaluated
- The foreign and translated word-pairs were encoded and stored in the memory only if the second word of a pair was repeated 2-4 times during the "Up-state" phase of brain activity
- For example, foreign word-pairs "tofer" (key) or "guga" (elephant) played during deep sleep were accurately interpreted as "something small" (tofer) or "something big" (guga) after waking
- This study demonstrates for the first time that foreign words and translated words can be associated during sleep and the associations can last until waking
Concluding RemarksThe evidence arising from the current study suggests that the existing theories on sleep and memory could be seriously challenged and may require a thorough revision in the light of the new findings. The present understanding that sleep is a state of mental detachment from the physical world, may no longer be justifiable. Importantly, the findings indicate a paradigm shift in our theoretical understanding of memory and consciousness and their interrelationship.
"We could disprove that sophisticated learning is impossible during deep sleep", says Ruch.
Henke concludes: "In how far and with what consequences deep sleep can be utilized for the acquisition of new information will be a topic of research in upcoming years."
Funding SourceThe study was funded by the University of Bern, Switzerland.
- Implicit Vocabulary Learning During Sleep is Bound to Slow-Wave Peaks - (https://doi.org/10.1016/j.cub.2018.12.038)