Sleep learning, or hypnopedia, has been widely promoted. There are many advertising messages claiming that all you have to do is let the lesson “play” while you sleep and when you wake up you will have acquired a set of knowledge. Is this true? What does science say about it?
The beauty of the method is that it requires little effort to achieve the results it promises. Supposedly, you learn without making any effort. And, in theory, you learn well: you end up knowing something new without realizing it and without any hiccups or mistakes. This is seen as a panacea for those who are not very fond of studying. You go to sleep ignorant and wake up knowledgeable.
“ Any unnecessary aid is an obstacle to development .”
-Maria Montessori-
As an advertising topic, it is certainly very attractive. However, in practice, things can be very different. Perhaps marketers have started from a scientific basis, but somewhere along the way they have taken it much further than it can go. Let’s see what it’s all about.
Learning during sleep
First of all, it must be said that learning is a process through which a transformation in a person’s perspective or behavior occurs, based on acquired experiences. Such experiences can be physical or mental. In any case, the definitive thing is that after learning something, the person is no longer the same as before.
On the other hand, learning is not only what is consciously remembered. Memory is only one part of that process. Learning not only generates memories but also changes in attitude, in the way of doing things and seeing reality .
Now, during sleep there are basically two phases: paradoxical sleep and non-paradoxical sleep . The first is also called “rapid eye movement” sleep, or REM. Science has discovered that there is a relationship between this phase of sleep and memory consolidation. However, these mechanisms are still not fully understood.
However, it has been established that the memory that is consolidated during this phase is long-term. It is also established that if a person is deprived of this period of sleep, not only does forgetting occur, but also a state of stress . If a person receives external stimuli during this phase, he or she will not rest properly. Despite this, is learning possible during sleep?
A suggestive experiment
To establish whether learning during sleep is possible, an experiment was conducted at the Weizmann Institute in 2014 , which was later published in Nature Neuroscience . The experiment involved learning through conditioning. Sleeping volunteers were given a series of bells with different pitches to ring. At the same time, a scent was broadcast. This was repeated several times, but in the end the olfactory stimulus was removed.
The next day, some members of the same group were consciously subjected to the sound stimulus. The result was that almost all of them experienced the aroma of the previous night, even though it was not present. In a word, they had “learned” to associate both stimuli, while they were asleep .
This leads to the conclusion that it is indeed possible to generate a certain type of learning during sleep, although with very precise limits. First, what was generated was a completely mechanical learning, without rationalization . None of those who participated in the experiment remembered what happened the night before. Likewise, over time they also stopped associating sound and smell. Therefore, it was all a very basic and ephemeral learning.
Some partial conclusions
What did surprise the Weizmann Institute scientists was that the learning during sleep, however limited, had been acquired in phases other than REM . Apparently, the brain is more receptive to external stimuli during REM sleep, but in the experiment the opposite was true.
The truth is that we still don’t know much about sleep than we know about it. What is clear is that it is a fundamental process for human beings. When we sleep, the brain does a kind of cleansing, eliminating useless data and consolidating relevant data . At the same time, when we don’t sleep well, there are negative consequences for our health.
So far, there is no evidence for learning during sleep, at least for subjects that require reasoning . Nor is there any certainty about the duration and extent of any learning that occurs during sleep . So, for now at least, we will probably continue to learn in the traditional way.