Sleep and memory
You need to sleep more often
Anastasia Kazantseva, STRF.ru
Vladimir Matveevich Kovalzon, a leading researcher at the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, a specialist in the field of physiology, biochemistry and pharmacology of sleep, Doctor of Biological Sciences never scolds students who fall asleep at his lectures. The scientist knows that even a short sleep helps to consolidate memory and it is better to miss five minutes, but firmly learn everything else.
However, none of the listeners fell asleep at Kovalzon's public lecture "Sleep and Memory", held at the Darwin Museum on January 25 as part of public readings dedicated to the centenary of the magazine "Nature". It is absolutely impossible to sleep when the foundations of the world order are being shaken before your eyes. The audience has always suspected that civilization forces people to live according to some stupid schedule, but they did not expect that this is a universally recognized scientific fact.
Fast and slowFrom a state of calm wakefulness, a mammal can move to a slow sleep.
It is divided into four stages (the first is superficial sleep, the fourth is deep). After the animal passes them all and returns back, the rem sleep phase, or the phase of rapid eye movements, begins.
Kovalzon notes that it was sleep research that became the first "intersection point of electricity and the psyche." It is today that scientists can use MRI to determine brain areas associated with a wide variety of things – from facial recognition to the idea of housing. In the first half of the XX century, they had only an electroencephalograph at their disposal, and it was with its help that they discovered that brain activity during different stages of sleep differs very markedly. At the same time, slow sleep with its low-frequency waves cannot be confused with anything, but the electroencephalogram of rem sleep for an inexperienced observer is very similar to the EEG of a waking person. Only additional data on muscle activity and eye movements can distinguish them with confidence.
Sleep cycles are characteristic of all mammals. After the slow sleep stage, a fast one comes, and then the animal either wakes up or moves on to a new cycle. A person's night sleep normally consists of 5-6 such cycles, each of which lasts about an hour and a half. In a good way, it would be necessary to wake up at the end of the cycle. "An intrusion into a night's sleep, say, an alarm clock, is generally a very unpleasant thing for the whole system: for our brain, for behavior, knocking us out of a rut," the lecturer confirms. "Attempts have been made repeatedly to develop such an alarm clock that would track our condition and wake us up at the end of the cycle. Let it be even up to the moment when you really need to get up, but it's better to wake up earlier at the end of the cycle than in the middle of the next cycle we will suddenly be woken up." Today, there are no such alarm clocks on the market yet – existing samples measure the pulse, and only an encephalogram allows you to determine the sleep phases with acceptable accuracy.
But human sleep differs from the sleep of normal animals not only in that we get up on the alarm clock. The structure of cycles has also changed: in the first half of the night, a person has a large proportion of slow sleep, and closer to the morning, the proportion of fast sleep increases. Kovalzon explains that this feature is also associated with the pressure of civilization, which forces us to sleep only once a day – at night. As a result, the body first gets the vital slow sleep, and in the remaining time pays attention to the fast.
Anthropological studies of primitive cultures confirm that the structure of our sleep is dictated by lifestyle. "It has been shown that in natural conditions a person sleeps during the day. And not even once, as our children sleep, but twice. This is the natural nature of sleep for an adult, which is recommended to him by genes," says the lecturer. – And at night he sleeps less and his sleep structure is different, these sleep cycles are uniform, and the difference between the first half of the night and the second is erased."
How can genes tell us when to sleep? At least as far as the 24-hour rhythm is concerned, there is already clarity. The main role in maintaining the daily cycle is assigned to the "biological clock", which are located in the suprachiasmatic nucleus of the hypothalamus. Our watches are equipped with a pendulum, which acts as various molecules, such as protein PER. Like any protein, it is synthesized in two stages: first, a gene is read and information RNA is synthesized, and then an amino acid sequence is built on it. These two stages are separated by time: when we sleep, RNA is synthesized in neurons, and when we are awake, a protein is formed that binds to its own gene and prevents the production of RNA. This system is connected to the retina, and it adapts to daylight. If these hours are not let down, most people will have them working on a 25-hour schedule.
What does memory have to do with it?The idea that one of the most important functions of sleep is the ordering of acquired experience is confirmed by many experiments.
Today, the scientific community no longer doubts the very fact that sleep is necessary for effective memorization of new information and is mainly engaged in finding out which types of memory are most dependent on sleep and which sleep characteristics affect the process of memorization.
Most experiments are related to declarative, or conscious memory. For example, subjects can be offered a list of words to memorize, and the next morning compare the effectiveness of reproducing these words in those who slept at night and those who were awake. Of course, sleep-deprived people reproduced words worse. "But it was something else that was surprising. When these words were divided into emotionally positive, emotionally neutral and emotionally negative, it turned out that emotionally positive words are very much forgotten after a sleepless night, while negative ones are not. That is, we remember all sorts of rubbish, so to speak, troubles best of all," warns Kovalzon.
What exactly happens when people lack sleep is quite difficult to investigate. It is much easier to work with rats, and in their case, a clear link has been established between sleep and the restoration of the level of proteins necessary for memory processes.
In many experiments, people are asked to sleep during the day, shortly after learning a skill. It turns out that those who slept even for a few minutes reproduce what they were taught (for example, playing the piano) better than their colleagues who did not manage to sleep. However, the next morning the second group can catch up and even overtake the first, and a day later – there are no significant differences anymore. "This shows that for our good memory, it does not matter when we slept – day or night, but it is important that consolidation takes place during sleep. This dream dramatically improves consolidation, that is, the transition from short–term to long-term memory," explains the scientist.
In another similar experiment, a tomographic study was conducted, during which experts compared the activation of different brain areas when performing a motor task before and after sleep.
It turned out that after the sleep of the subjects, the activity of the brain areas responsible for the arbitrary regulation of movements decreases, but the work of the zones associated with the automation of actions increases.
An interesting feature of the effect of daytime sleep on memory was demonstrated in the work carried out by Kovalzon together with specialists from the Institute of Higher Nervous Activity and Neurophysiology. In this experiment, the subjects were asked to memorize pairs of words, and they learned some of the material twice, and some only once. It turned out that in the first case there was no significant difference in the reproduction of words between people who slept and those who did not sleep, but the words that the subjects learned only once were reproduced better after a nap. "What does this mean? If we have learned something badly, then it is all the more important to sleep. Because if you have learned badly, then you will definitely not remember without sleep. If you have learned very well, then you can already do without sleep," says Kovalzon.
Brave New World"Rather than fix the old, it's better to buy a new one," the sleeping cubs were taught in a book by Aldous Huxley.
Unfortunately, the children have not learned anything. The idea of hypnopedia, sleep training, has been seriously discussed by scientists, but numerous experiments have shown that this method does not work. The brain perceives information well in a state of calm wakefulness, but after falling asleep, it reliably shuts itself off from external stimuli and works only with the information that it managed to get earlier.
A page from the American magazine "Illustrated Mechanics" for November 1958.
The caption reads: "Learn in a dream. A whisper from under the pillow will help you learn anything –
from self-confidence to higher mathematics."
Modern scientists are sure that the method of hypnopedia (sleep learning) does not work
Nevertheless, the very idea of Huxley's book – the organization of the world taking into account the achievements of modern biology – looks very attractive. If a neurophysiologist became the president of the country, our life would undoubtedly change for the better.
Firstly, we would be better taught at school, because education would be built on understanding the mechanisms of the brain. Experts know that it takes at least two hours to transfer information from long-term memory to short-term memory, which means that the class-time system is ineffective, because the information received in the lesson prevents the memorization of the previous lesson. "And then they wonder why schoolchildren or students do not assimilate well… It's amazing that they learn anything at all!" the lecturer is indignant.
Secondly, we would have fewer accidents, errors in treatment and other problems related to the human factor, because a significant part of them is due to lack of sleep. The activity of a modern person requires intense concentration of attention. "For such a regime, we need a constant highest level of brain activity, we must always be as alert as possible. And this is very difficult. If you haven't had enough sleep, then it's simply impossible," says Kovalzon. – Now it is very hotly discussed. There were materials on the Internet on the topic that in New York they made rest rooms for clerks where you can sleep. This is very reasonable! I would like to have such things organized here, too, where a person would not just be able to have lunch, but to have the opportunity to retire to this sleepy office <...>. This greatly refreshes the brain and relieves the pressure of sleep, which <...> persists due to the fact that we do not have the opportunity to sleep during the day. Therefore, it is vitally important for a modern person, both for himself and for others."
Another way to dramatically reduce the number of problems arising from lack of sleep is to refuse to switch to daylight saving time. "The danger lies in frequent regime changes. Somnologists and specialists in biological clocks always recommend that modern people try to change it as little as possible. If you are used to some kind of rhythm, even if it is strange, then you stick to it, because your body systems have been rebuilt and the clock is already ticking in this mode that you have chosen for yourself. Therefore, we always oppose the change of winter-summer time," the scientist explains.
Thirdly, we would get rid of traffic jams and social tension between "larks" and "owls". Despite the fact that most people still belong to the type of "pigeons", that is, they are able to adjust to any schedule, there are also innate "larks" and "owls". Due to genetic characteristics, the internal clocks of such people are always in a hurry or lagging behind, which means that fatigue occurs noticeably earlier or later than in an ordinary person. Kovalzon believes that everyone should have the opportunity to get enough sleep, even if he is a mutant.
The good news is that recently the heads of firms increasingly share this idea: "People need to work – not to dig the ground, but to do some kind of work that requires high mental stress, mobilization of all cognitive abilities. To do this, you need a person to be in good shape. And the heads of firms allow employees to choose the mode that is convenient for themselves, as long as the work is done. In addition, it unloads transport – the more smoothly people start working, not everyone goes there and back at the same time. That is, it has a number of advantages, and now this idea is already finding application."
Portal "Eternal youth" http://vechnayamolodost.ru
28.01.2011