Learning in Sleep; From Imagination to Reality. Studies conducted in recent years show that the brain can consolidate what has been learned and learn new things during sleep. The idea of learning in sleep was first proposed in a novel called “Brave New World” by Aldous Huxley. The novel describes a society whose citizens were distorted by the various instruments of those in power and wealth and were by no means independent. In this story, scenes are depicted where recorded sounds were played to children while they were sleeping so they could be prepared for their future roles in society. Despite the dark and scary ending that Huxley depicted in this story at the time, the idea of sleep education was so appealing to readers that after the novel was published in 1932, there was massive enthusiasm for sleep learning.
The beginning of research on learning in sleep
In 1951, two researchers at George Washington University in the United States decided to investigate this phenomenon scientifically. They placed a tape recorder and speakers in the bedrooms of 30 volunteers. These people were divided into two groups, and one night for half an hour during sleep, music was played for one group, and a series of Chinese words with their meanings in English was played for the other group. In the test that took place the next day, it was found that those who had heard Chinese words during their sleep performed better in answering the questions of the Chinese language test.
About half a century ago, some scientists claimed that it is possible to learn things while sleeping.
In this way, the researchers concluded that “learning also takes place during sleep.” At that time, some other researchers also started to do more studies about this. Another research team experimented and announced that they could teach Morse code (an ancient method of communication between ships) to a group of maritime university students while asleep. Also, another group of researchers announced that by broadcasting the sentence “My nails taste very bitter” to children who chewed their nails, they made them stop this habit. In that study, the researchers played this sentence six times during the night for 54 nights to these children.
Doubt about the correctness of the research
But very soon, the validity of these research findings was questioned. One of the objections raised was that the participants were not monitored during the experiment, so it was unknown whether they were asleep. In 1955, after doubts were raised about the accuracy of the previous research, other scientists re-examined this phenomenon. This time they also evaluated the sleepiness of the participants using an electroencephalogram (EEG) recording device. It was here that it became clear that people who were asleep did not learn anything, so all previous research in this field was rejected. In this way, the issue of “learning in sleep” was forgotten.
A renewed passion for further research
But in the last few years, the problem of learning in sleep has again attracted the attention of researchers. The studies conducted during this period show that the human brain can receive new information during sleep under certain conditions. Various studies conducted in the field of different neural stimuli make the perspective of learning during sleep clearer.
Today, human knowledge has much more understanding of brain activities during sleep than in the past. Interestingly, the volume of our expertise in this field has increased significantly only in the last decade. As mentioned, in the past, some scientists used the brain activity recording device (EEG) to study the phenomenon of learning in sleep. “Electroencephalograph device” or “brain wave recording device” (EEG) records brain activities in the form of a series of waves. One of the exciting things that can be seen in the use of this device is that brain activity does not stop during sleep. Today, the brain revises and stores daily memories during sleep to store more critical information.
The effect of smell in consolidating memories
In 2007, a neuroscientist named Dr. Jan Born and his colleagues at the University of Lubeck, Germany, investigated the possibility of controlling the process of reviewing memories in sleep. They asked 18 research participants to play a mental game before bedtime. In this game, each person must remember the position of 15 pairs of images that appeared on the computer screen. While playing this game, the participants also smelled a red flower. Then during sleep, half of these people were again exposed to the scent of roses. The research team believed this would consolidate their learning as much as possible.
Being exposed to a specific smell during learning and then sleep leads to recalling more and more of what has been learned
The choice of “smell” as a stimulus was not unreasonable because this factor (unlike other factors such as “sound” or “light”) did not disturb people’s sleep and did not wake them up. Also another compelling reason for this choice is the close connection that smell has with memories. Some brain areas that process smells are directly connected to the hippocampus. It should be noted that the hippocampus is a part of the brain that plays a vital role in forming memories. The result of this experiment confirmed the prediction of scientists. It was found that people exposed to the scent of roses during sleep could remember the pair of images seen more after waking up than the second group.
The effect of sound in consolidating memories
Sometime later, Dr. Ken Paller, director of the cognitive neuroscience program at Northwestern University in the United States, who was influenced by the study of the effect of smell on the consolidation of memories, decided that the role of another stimulus, “sound” to check the ability to remember memories better. Dr. Paller organized an experiment for this purpose. Participants in this experiment had to reflect the position of 50 images on the computer screen. A sound accompanied each portrait. For example, the image of “cat” was accompanied by the sound of a cat, and the appearance of “kettle” was accompanied by the sound of a whistle after boiling water. These people would fall asleep after working with these images. Then the researchers played half of these sounds to them while they were sleeping. After the subjects woke up, their ability to recall the position of the images was measured.
Hearing some unique sounds during sleep can consolidate the learned things as much as possible.
As these researchers predicted, people who had heard sounds related to these images during sleep could remember the location of the photos related to those sounds more than the group that heard unrelated sounds. Hearing the sounds associated with each image increased the probability of remembering the location of that image.
Learn music better
The successful completion of this research made Dr. Paler think about this method’s effectiveness in music education. In another study, he concluded that people who learn to play a particular piece of music, if they hear it during sleep, are better able to play it again after waking up.
Waiting for the exam
In 2011, another group of researchers investigated another factor that strengthens the process of consolidating memories in the brain. Participants had to memorize a set of word pairs in an experiment set up before falling asleep. Half of these people were told they would be tested the following day.
In the end, it was found that people who thought they would have to present their learning in the exam tomorrow performed better in remembering these memories than those who did not know about the exam or did not sleep despite knowing about it. Scientists concluded that waiting to be tested and sleeping afterward can force the brain to repeat and reinforce the learned as much as possible. If you think we need to remember what we learned during an exam, the probability of remembering it increases during sleep.
Deleting and forgetting information
As mentioned, the brain consolidates some information and daily memories during sleep. But another task of the brain is ignoring and eliminating unimportant events. Can this feature of the mind be used in line with constructive goals? Dr. Paller once again organized a study in this field. In this research, he found that it can weaken people’s established mental teaching, such as “women are weaker than men in the field of learning experimental sciences” during sleep.
Erase bad memories
All of us may have bad memories during our life. Some of these unpleasant memories for some people may even disturb the normal process of life and thus cause many problems for them. But can the brain’s ability be used in sleep to erase these memories?
A study conducted by Dr. “Katherina Hauner” a few years ago found that this is possible. In this research, the participants were first shown pictures of several faces. During the broadcast of these images, they were given a mild electric shock, or they were exposed to a pleasant scent of mint or lemon. In this way, the pictures accompanied by electric shock were recorded as unpleasant memories in people’s minds.
Then these people would go to sleep. During their sleep, they were only exposed to pleasant smells and no electric shock. At first, this work caused anxiety in these participants during sleep. Scientists used to notice the presence of this anxiety by measuring the sweat created on the skin, but gradually this anxiety disappeared.
Using unique methods during sleep can reduce the intensity of negative memories.
Examining the reaction of these people after waking up to images that were previously associated with shock resulted in far less anxiety, but in the participants who had gone through the same steps while waking up, no change in their anxiety level was observed.
All these studies showed that the brain could receive new information during sleep and strengthen or weaken the process of consolidating some info. As a result, can we conclude that the scientists who claimed education during sleep more than half a century ago were not so wrong? The two new pieces of research that have been done in this field confirm the claim made a few decades ago about learning in sleep.
Communication of sound with the smell
In the first study, Anat Arzi and her colleagues in occupied Palestine investigated the effect of smell and good communication during sleep. In this study, subjects were exposed to a specific sound with a pleasant smell (such as the smell of deodorant) and another particular sound and a foul smell (such as the smell of rotten fish) during sleep. All these events happened during sleep, so they did not know about this issue. After awakening, each sound was repeated to these participants separately without odor.
Humans normally breathe deeper when faced with pleasant smells and take shallow and non-deep breaths when faced with unpleasant odors. The researchers were surprised to see that these participants were in the awake state; as soon as they heard again the sound that was accompanied by a pleasant smell in the dream, they breathed more deeply. The depth of their breathing decreased when they listened to the sound accompanied by an unpleasant smell in the dream.
Quit smoking in your sleep!
If the brain can be taught during sleep to communicate between two stimuli, the person can entirely unconsciously show a behavior related to these two stimuli. This ability of the brain can be used to teach specific behaviors to people. Did Dr. Anat Erzi organize another study this time? There were 66 smokers in this study. During the time these people slept in the laboratory, they were exposed to the smell of cigarettes along with the smell of rotten fish or rotten eggs. After a week of this experiment, it was found that these people’s tobacco consumption had decreased by 30% compared to the previous week. Interestingly, a group of participants exposed to these two odors while awake (and not asleep) did not show such behavior, and there was no change in their tobacco consumption. The effectiveness of this method only depended on its implementation during sleep.
Using an odor stimulant during sleep can even lead to smoking cessation in smokers.
Brain in sleep
This study and other research that we mentioned show that during sleep, the brain undertakes a unique process to process memories, increasing the ability to create connections between stimuli. However, we still need to learn more about how this process works.
Another finding of the researchers was that learning rarely occurs during REM sleep. The word REM stands for Rapid Eye Movement. During this part of sleep, our eyes move rapidly; during this stage, we dream.
On the other hand, this communication between stimuli occurs mainly during a part of sleep called “slow wave sleep.” Short-wave sleep is deep sleep in which brain cells go from inactivity to activity and vice versa in alternating periods. In fact, in this part of sleep, the activity of brain nerve cells varies greatly.
Some scientists believe that short oscillations of brain waves during this part of sleep can lead to the consolidation of memories. This process may also prevent dreams from being confused with real memories. The results of the studies we saw show that the brain can create a connection between some stimuli (such as smell and sound) during sleep. But is it possible to learn a set of verbal information during sleep?
Learn more while you sleep
We have known for years that the part of the brain responsible for processing verbal information remains active during sleep, and that is why if someone calls our name while we are asleep, we are more likely to wake up than when someone else’s name is called. During this period of unconsciousness, let’s hear.
The same issue made another group of researchers think about the possibility of processing verbal information by the brain while sleeping. In one study, participants were asked to categorize the words they heard. These people were asked to press a button with the “right” hand whenever they listened to the name of an “animal” and another button with the “left” hand when they heard the name of an “object.” It should be mentioned that pressing the button with the “right” hand causes the activity of the “left” hemisphere, and the activity of the “left” hand also causes the reaction of the “right” hemisphere.
The participants performed this activity while awake, and their brain activity was also recorded by an electroencephalogram (EEG) device. After some time, these people were asked to lie on a comfortable bed in a dark room and sleep whenever they wanted. These people kept pressing the relevant button until they fell asleep.
The brain processes incoming information even during sleep.
After people fell asleep, no more buttons were pressed. However, the device’s examination of their brain activity showed that their brain activity did not stop, and the hemispheres still responded to the announced names. Their unconscious mind was processing the meaningful input information; of course, this processing speed was relatively slower than the conscious state.
In this way, it was found that the brain can not only receive meaningful verbal information during sleep but can also process it and even give an appropriate reaction to it. As the brains of the participants in this study continued to categorize words even while sleeping, this method could be used for learning in sleep.
The world of learning in sleep: fears and hopes
If it is possible to provide the possibility of learning in sleep, we can witness a revolution in education. Some scientists believe that in the future, this method can be used to improve the teaching of skills such as music, foreign language, or even sports skills. Also, it may be possible to eliminate some ugly habits, such as smoking and even hating certain foods. It also weakened the possibility of reducing false beliefs such as racial discrimination.
On the other hand, some scientists believe that sleep plays a vital role in our mental and physical health, and purposeful use of this opportunity to rest and recover from giving it more information may disrupt the natural process of human life. However, it may be too early to conclude the effectiveness of sleep training. Future studies by scientists may reveal new aspects of this issue.
Learning a foreign language in a dream
Although it may be impossible to learn a foreign language in sleep, there are ways to use rest to increase the possibility of memorizing and recalling what you have learned.
- Take a nap: If you sleep immediately after learning something new, the possibility of remembering it increases significantly. For this reason, napping during the day can strengthen new memories and learning.
- Using smells: One of the best ways to learn is to use a specific scent. If you are in an environment with a pleasant smell like mint during learning and smell this smell while sleeping, the new understanding will be more fixed in your mind.
- Anticipation of the test: the expectation that we have to evaluate what we have learned in an exam increases brain activity to remember them. For this purpose, you can plan a simple test after learning a specific subject and then go to sleep. During sleep, your brain will consolidate what you have known for the test.
If reading this article was helpful, we suggest you also read the “How to Motivate Apathetic Students?” article.