And yet... Is it possible to learn while sleeping?

The topic of sleep learning , or hypnopedia, has attracted the attention of researchers for many years. The basic idea is that a person can learn and remember information while sleeping, for example, by listening to audio recordings.

However, scientific research in this area has yielded conflicting results.

1. On the one hand, there is evidence to suggest that in a certain sense, sleep learning is possible: some studies have shown that reproducing certain sounds or smells associated with learning before sleep can enhance memories associated with those stimuli.
2. On the other hand, research highlights the limitations of this method. Although the brain continues to process information during sleep, the level of conscious perception and the ability to actively learn are significantly reduced. Sleep is important for consolidating memories and processing information received in the waking state, but the active assimilation of new knowledge in sleep seems to be beyond human capabilities.

Who even decided that people could learn in their sleep?

The fact is that during sleep, the brain is still able to process external signals, and this can affect memory processes; This fact is key to understanding the potential of sleep learning.

Indeed, the brain does not completely "shut down" during sleep and continues to register certain types of signals coming from the outside, which is supported by many studies.

There are two types of memory: implicit and explicit.

• Implicit includes things like motor skills and habits that are formed unconsciously.
• Explicit refers to memories that we form and retrieve consciously, i.e., real-life events.

When it comes to sleep, different phases (REM and NREM) play different roles in memory processes:

• REM (REM Sleep). It is often associated with dreams and dreams; may play a role in the processing of emotional memories and in the consolidation of implicit memory.
• NREM (slow-wave sleep), during which explicit (declarative) memory is consolidated. This phase is especially important for processes such as learning and information processing.

How the meta-analysis was conducted

A team of researchers conducted a meta-analysis of 51 studies involving living subjects, starting with the earliest studies on the topic; Although there have also been animal studies related to sleep and sleep learning (which have shown some positive results!), these studies were not included in the meta-analysis.

The main focus of these studies was on memorizing verbal information. Such experiments included studying the content of educational materials (similar to the film "Big Break") or teaching foreign languages:

• Expand vocabulary to include new words and terms;
• Mastering grammar rules, vocabulary and syntax;
• Perception, analysis and processing of sound speech.

A key question for the researchers was whether the knowledge supposedly learned during sleep could be transferred to the waking state and used in real life.

Mixed results

Some of the studies reviewed in the review point to the ability of a sleeping person's brain to process nerve impulses and form memories. However, the question of whether these memories can be used in the waking state remains open.

• The first study in this area was conducted in 1952; The report claimed that participants in the experiment were able to recall songs played while sleeping. However, the study did not use electroencephalographic (EEG) confirmation of sleep, casting doubt on its accuracy.
• The other two showed contradictory results. One indicated that verbal information reproduced during sleep could be better assimilated; Others, on the other hand, found no advantage in learning information during slow-wave sleep.
• Two more experiments showed that the level of information assimilation during sleep was slightly higher than random, despite the fact that the experiment lasted five nights. In addition, hypnosis was used in the experiments to induce sleep, which may have affected the results.
• Two more experiments focused on studying brain activity during sleep memorization of pairs of answers and questions, simple terms. Both demonstrated that the subjects could only recall information in a state of alpha activity, that is, not sleep, but relaxed wakefulness, which was confirmed by medical parametric data.

All these studies were aimed at the study of explicit memory, that is, consciously formed and retrieved memories. However, there is also research on the retrieval of verbal information received during sleep in the unconscious state.

1. One of them investigated the processes of memorizing pairs of words representing a general concept and a narrower, more specific example of it, for example, "tree" and "oak". In the experiment, subjects were given pairs of terms to listen to either while awake or asleep. The results of both groups were then compared. The group that studied the words in their sleep showed no results.
2. In another study, participants were given unknown words in their sleep — upon awakening, the participants did not perceive or recognize the terms. However, an EEG study showed that their brains reacted to these terms as if they were known words, not new ones! Memorization thus took place, but the practical meaning of possessing knowledge that a person could not use remained questionable.
3. A new study has found that a person can involuntarily memorize words during the slow phase, but not the other way around. Participants were shown a picture and allowed to listen to the corresponding audio sequence, such as a picture of a dog and the sounds of barking. Then, while sleeping, they were given this sound and the corresponding word in Japanese, which none of the subjects knew. After waking from the dream state, the participants took a test where they were given a Japanese word and shown a couple of pictures of their choice. Words heard during slow-wave sleep were recognized as familiar, while words from REM sleep were not.

In general, the question of whether a person can study while sleeping remains open. If by "learning" we mean unconscious memorization followed by conscious retrieval of it, then the answer is rather negative: that is, learning a language in a dream without making an effort will not work. But you can memorize words in a dream - it's just a pity that you won't be able to use them in reality.

What else do we know about slow-wave sleep training?

A relatively recent study by researchers at Harvard Medical School and MIT in Chicago has opened up interesting avenues for understanding the link between creativity and sleep. By using targeted dream incubation, scientists are likely to be able to influence a person's creative thinking.

The experiment used a Dormio device that tracked the onset of the desired phase, and then woke up the subjects to record their dream stories. The device has also been used to induce certain themes through sound signals, in this case trying to induce a dream about a tree.

The 49 subjects were divided into two groups: one was trying to provoke dreams on a given topic, and the other served as a control. Afterward, the subjects recounted their dreams, which were carefully analyzed. Participants then performed creative work involving the use of the word "tree" in different contexts and matching verbs to different nouns related to the theme of the tree.

The results showed that the participants in the experiment outperformed the control group in creativity, coming up with more original and diverse ideas. A positive correlation was found between the frequency of a keyword mentioned in dream reports and creativity, so that dreams focused on a specific topic were able to increase a person's creativity.