Scientists thought for a long time that the brain stopped communicating with the outside world and consciousness was temporarily lost during deep sleep phases. So, by doing this your brain; It was thought that he could pass the memories learned during the day and store these memories without any external intervention. This was called memory enhancement, and there are a lot of studies showing that sleep is very important for this process.
At the moment of sleep, the idea that our minds close themselves to the outside world is quite old. In spite of our daily experience and current scientific studies that show that our brain does not completely shut itself to the outside world during sleep, this point of view can be included in our understanding of sleep even today.
However, it is evolutionarily logical that we do not fully relate to the outside world, to be protected from a predator hidden anywhere. That’s why the brain leaves the door between the outside world a little, and so we can wake up in the voice of any intruder. For example, we easily wake up when we hear our own name or when you hear a particularly remarkable sound (e.g. alarm sound) compared to other sounds of the same intensity.
Current research shows that complex stimuli can not only be processed during sleep, but this information can be used to make decisions just like when we are awake.
Our brains can automate many complex jobs quickly. For example, driving a car requires being able to integrate a lot of information at the same time, make quick decisions and implement these decisions quickly with complex motor skills. And after work, you can drive directly to your home without remembering anything (as if you were an autopilot).
During sleep, the brain areas of our brain that are necessary to follow the attention and instructions become passive, making it impossible to perform a task at sleep time. In a study published in Current Biology, the research team asked the participants to see if any processes in the brain were ongoing from the moment the sleep began, on an automated task given just before sleep.
In the experiment, the participants were asked to categorize the verbal words divided into two categories. For example, in the first experiment, like animal and object names (cat or hat), in the second experiment, real words – for example, hammer-like and false words (i.e. words not found in the dictionary) -for example; fabu- was used.
Processing External Voices in Sleep
The participants were asked to press the left or right button to determine the category with the word they heard. When the task began to become automated, participants who were about to sleep were asked to continue reacting to words. Most of the participants, lying down in a dark room, fell asleep while the words continued to be heard.
In the experiment, the awake states of the participants were observed thanks to the EEG electrodes placed in their heads. After understanding that they fell asleep, the participants started to listen to other words in the same category without disturbing their word flow. The purpose of doing this was to extract the meaning of the word played in the first experiment, or to force the answer to check whether the word played in the second experiment actually exists in the dictionary.
Of course, as expected, as soon as they fell asleep, participants stopped pressing the buttons. So, in order to understand whether their brains still react to words, activity in motor regions in their brains was observed. If you plan to press the left button, activation will appear in the right hemisphere of your brain, and if you plan to press the right button, an activation will appear in the left hemisphere of your brain. Therefore, by looking at this lateralization in brain activity in the motor regions, it is possible to see which side will be directed for someone’s response. In the experiment, it was seen that the participants were prepared for the response of pressing the right or left button according to the meaning of the word they heard, even during sleep.
At the end of the experiment, it was seen that when the participants woke up, they could remember the words they heard before falling asleep, while they could not remember what they heard during sleep. This shows that they process complex information at the time of sleep and, moreover, they do it unconsciously. The findings reveal that the brain has the ability to process information during sleep and unconsciously.
Of course, this research is only the beginning and most of the important questions have not been answered. For example, if we can prepare for our actions at the time of sleep, why don’t we do it? In other words, despite activation in the left or right motor regions in our brain, why do not we press the buttons? What are the things the sleeping brain can and cannot do?
Can sentences or phrases be processed during sleep? What is happening in our brains when we are dreaming? Are voices heard from the outside world during dreaming included in the dream? And many more questions are waiting to be answered. However, a more important age-old fantasy also stands before us: Learning to sleep. We know that sleep is important in strengthening previously learned knowledge or some basic forms of learning such as conditioning. Well, can more sophisticated forms of learning come true and if so; What is the cost the brain will pay to do this?
Sleep is extremely important to our brain, and a sleep of about 2 to 4 weeks can cause death. It should be borne in mind that sleep is a vital phenomenon and universal for all animals. In addition to all these, it is not to force our brains to learn during sleep, but to learn by spreading them over a long term; it will also be beneficial for our brain and overall health.