Sleep

Sleep is a natural physiological process of stay in a condition with minimal level of brain activity and reduced reaction to the world around us.

Sleep is essential to person to ensure the rest of the body, processing and storage of information, elaboration of unconscious models of expected events, organism's adaptation to changing light conditions (day and night) and recovery of immunity. In normal adult and healthy person it should last about 8 hours but depending on the situation this period can be from 4 to 10 hours. The sleep normally, sleep occurs cyclically, roughly every 24 hours. These cycles are called circadian rhythms.

In the history of "science of sleep" the important role played by the research of M. M. Manaseina (1843-1903), which in the 1870s came to the conclusion that sleep is for the body more important than food. Modern ideas about the nature of sleep emerged in the second half of the XX century, after the advent of methods of registration of bioelectric activity of the brain, muscles and eyes. A major achievement in this area was the discovery in the 1950s N. Kleitman, W. Dement (USA) and M. Jouvet (France) the phenomenon of "paradoxical sleep".

Now in addition to the physiological characteristics of sleep study of its psychological characteristics.

Physiology of sleep

Just before sleep induces a state of drowsiness, reduced activity of the brain. It is characterized by a decreased level of consciousness, yawning, lowering of the sensitivity of sensory systems and the secretory activities of glands (as a consequence of the sticking of the eyelids), as well as the change in heart rate.
The structure of the dream consists of a series of steps, regularly repeated during the night, the appearance of which is due to the activity of different brain structures.

In a healthy person the dream begins with the first stage of NREM sleep (Non-REM sleep), which lasts 5-10 minutes. Then comes stage 2, which lasts about 20 minutes. Even 30-45 minutes is between 3-4 stages. After that, the sleeper returns to the 2nd stage of NREM sleep, after which there is the first episode of REM sleep, which has a short duration – about 5 minutes. This entire sequence is called a cycle. On average, healthy sleep is celebrated for five full cycles. REM sleep cycle-to-cycle is lengthened, and the depth of sleep decreases.

REM sleep occurs immediately after falling asleep and lasts 80-90 minutes. It is divided into the following stages:

The first stage. Alpha rhythm is reduced and appear low-amplitude slow theta rhythms, amplitude equal to or greater than the alpha rhythm. Behavior: drowsiness with half-asleep dreams, absurd or mind-bending thoughts and sometimes giperalgeticheskie images (dream-like hallucinations). Muscle activity is reduced, decrease in the respiratory rate and heart rate, slows the metabolism and decreases the temperature, the eyes can make slow motion. At this stage can intuitively receive the ideas that contribute to the successful solution of a problem or the illusion of their existence. In the EEG can be recorded to a vertex sharp waves, occasionally observed hypnogogia hypersynchrony. In this stage may include hypnogogia twitching.

The second stage. A further decrease in tonic muscle activity. Heart rate slows, body temperature decreases, eye still. Is generally about 45-55 % of total sleep time. The first episode of the second stage lasts about 20 minutes. In the EEG is dominated by theta waves, a so-called "sleep spindles" — Sigma-rhythm, which represents the frequency of alpha rhythm (12-14-20 Hz). With the appearance of "sleep spindles" comes a loss of consciousness; in the pauses between the spindles (which occur approximately 2-5 times per minute) of a person is easy to Wake up. Occasionally sleepy spindles can be incorporated into the structure of stages 3-4 the perception thresholds Increase.

The third stage. slow sleep. The stage is classified as 3rd if Delta oscillations (2 Hz) is less than 50% and stage 4 — if the Delta is more than 50 %.
The fourth stage. The deep slow Delta sleep. Dominated by Delta oscillations (2 Hz). The third and fourth stages are often combined under the name of Delta sleep. At this time the person to Wake up is very difficult; there are 80% of dreams, and it is at this stage possible bouts of sleepwalking, night terrors, talking in your sleep and enuresis in children. But man most of them never remembers.

REM sleep is the fifth stage of sleep. The EEG observed fast oscillations of electrical activity, similar to beta waves and sawtooth waves.
 

sleep_002.jpg

During this period, brain electrical activity similar to the waking state. However, in this stage, the person is immobile due to a sudden drop of muscle tone. However, the eyeballs very often, and occasionally make rapid movements under the closed eyelids. There is clearly a link between REM and dreams. If that's the time to Wake up the sleeping, then in 90% of cases you will hear a story about a vivid dream.

Hypotheses about the causes of dreams

In oneirology, the science of sleep and dreams, the latter are related to the phase of rapid eye movement (REM). This stage occurs about every 1.5-2 hours of sleep and its length is gradually lengthened. It is characterized by rapid eye movement, which seemed to follow the movement of objects, stimulation of the Pons, increased breathing and heart rate, and temporary paralysis of the body. There is evidence that REM is not the only phase in which a person dreams – just at awakening in this phase they are the easiest way to remember.

Neurology as a scientific discipline combines features of neuroscience, psychology, and even literature, and trying to unravel the causes of dreams.

There are several hypotheses that try to explain the reasons why a person dreams:

Hidden desires
One of the first scientific approach to dreams used a well-known psychoanalyst Sigmund Freud in the early 20th century. After analyzing the dreams of hundreds of his patients, he came up with the hypothesis that dreams are the visualization of the brain is suppressed and unfulfilled desires.

A side effect of electrical brain
Another popular hypothesis says that dreams are really random side effects of activated circuits in the brain stem and stimulation of the limbic system associated with emotions, feelings and memories. Allan Hobson, a psychiatrist who popularized this idea, calls it "effective-synthetic model," according to which the brain tries to interpret random signals, which leads to the emergence of colorful or not so stories.

Encoding short-term memories to long term storage
Psychiatrist Zhang Jie proposed the hypothesis that the brain is constantly receiving a lot of memories, regardless of the fact that a man sleeps or is awake. At a time when short-term memories move into long-term storage in divisions of long term memory, and there are dreams.

Getting rid of "garbage"
The hypothesis of "reverse learning" suggests that dreams help people to get rid of some unnecessary associations and relationships that are formed in the human brain throughout the day.

Systematization of knowledge
This hypothesis is the opposite hypothesis of "reverse learning": according to it, dreams are a process of organizing and memorizing information.

In favor of this idea say several studies, the results of which show that people better remember information received just before going to sleep.

Defense mechanism
At the time of the dreaming brain works exactly the same as in wakefulness, except for the motor activity of the body. The same mechanism occurs in animals when they pose as a corpse in the hope that the predator will not touch them. According to this hypothesis, dreams are inherited from distant animal ancestors that have undergone the process of evolution some changes.

Imitation threats
Previous theory fits perfectly into the idea of famous Finnish philosopher and neuroscientist Antti Revonsuo. He suggested that the biological function of dreams is to simulate various dangerous situations to practice and "rehearse" reactions.

Solving problems
There is another, similar to the previous hypothesis, developed by Professor of psychology at Harvard University, Deirdre Barrett. She believes that dreams serve a person a kind of theater in which you can find answers to many questions and solutions to some problems, while in sleep the brain works more efficiently, because faster is able to form new associative links.

Natural selection thoughts
Psychologist Richard Coates, in turn, is sure that during sleep, the brain simulates various situations to choose the most appropriate emotional responses.

Smoothing of painful emotions through symbolic associations
Psychiatrist and researcher of disorders of sleep Ernest Hartmann believes that dreams are an evolutionary adaptation that helped our ancestors to cope with psychological trauma in a world where they had to deal with much more life-threatening events.

Previously, there was also a hypothesis linking the dreams with some mystic powers.

Mystical view of dreams

Absolutely all people are able to see dreams. Unfortunately, not all can remember about them after waking up. Dreams can be perceived differently – dull, black-and-white, discolored, or bright and colored (the latter usually for children or people with a strong imagination).
Since ancient times people attributed to dreams special mystical properties: communication with the higher powers and spirits, traveling to other worlds, predicting the future, the message of the ancestors and so forth.
Modern anthropologists have explored and documented the diverse ways of using the dreams of different nationalities in their everyday reality. We can say that here is a careful and respectful attitude to dreams, giving them special importance, since representatives of traditional cultures typically believe that the reality of the dream (in the case of a proper choice of the mode of action) can be provided conditions favorable for the development of events in the "day" of life.

So, the American Indians consider dreams as an important resource for the welfare of the tribe. The whole culture of the Australian aborigines based on dreams. They get the message of the deity and instructions that are applied in practice. African Zulus consider dreams as messages of the ancestors. The Indians, naskapi living in the forests of the Labrador Peninsula in Canada, rely on dreams as a guide to action in different situations. Naskapi - hunters, living in isolated family groups, separated by forests and swamps. They don't have a common tribal religion, tribal customs and cults, so they have to listen carefully to your inner voice, intuition and knowledge imparted to their life dreams. Naskapi believe that the "great man" can dream to give them advice or point you in the right decision, how to communicate with the outside world, with nature, how to do in a given situation. American Indians also give the dreams of great importance. For them, they are a versatile tool with which you can predict the future, solve problems of psychological and sexual persuasion, to heal the sick.

Many of the shamans and mystics to eminent scientists was trying to unravel an encrypted message. Initially, the dreams were understood to be directly (had the wound – wait wound), but in the beginning of our era there was a special sleeper, which helped to interpret dreams, based on a vision as symbols that are reflected in reality and the unraveling of dreams was engaged in a special priests. It was believed that a person during sleep moved into a special world, where he interacted with the gods and demons, deceased ancestors, spirits, etc. and received from them important and reliable information. Therefore, we first tried to find meaning in all dreams that people could remember, but then they were divided into "empty dreams" and "prophetic".

"Prophetic dream" necessarily carried the prediction of the future or gave a hint of the past. Such dreams often helped to determine the choice of something to find the lost item and to the Board. To determine what the dream was prophetic, and what – not, was extremely difficult until, until it came true, so were taken the first attempts to control these dreams by creating certain rituals.
For example, everyone knows the saying – "under Wednesday, and Friday dreams come true". Thus, on Tuesday and Thursday before falling asleep people up to a prophetic dream – recited prayers, asked the question the answer to which was interesting to him.

In addition to passive attempts to define the meaning of dreams, began to attempt communication with the spirits with special rituals: the use of various stimulating substances, physical effects on the body, placing the body in certain conditions, the practice of sleep monitoring. Dwell on the past.

Sleep management

In a separate group can be distinguished lucid dreaming. This term refers to a condition where a sleeping person (accidentally or intentionally developing this skill complex training) may be aware that he is asleep and sometimes even can manage the images or the course of events.

With this state people try to achieve different goals (here they are arranged in descending order of scientific evidence of the effectiveness of the application):

• self-knowledge;
• freedom from fears and phobias;
• the generation of ideas and subjects;
• attempts to know the future and hidden past;
• communication with the spirit world and journeys out of the body.

Since we consider only the mystical view, let us dwell on the last two paragraphs.

To know the near future or a specific hidden past (for example, where was the lost item) it is possible with sleep. This usually happens accidentally without the intervention of man himself (prophetic dream) and is due to the fact that a person physically perceives much more information than he realizes, while also unconsciously there is a continuous analysis of the situation. There is also the theory of a mystical order, explaining prophetic dreams, where sleep is seen as a journey in some kind of universal astral information system.

To obtain information on using lucid dreaming as possible, but not beyond what people "already know". The positive results of the attempts to get through the dream information about what people know could not, are on the level of coincidence. However, some proponents of this method argue that the performance improves after prolonged exercise. Unfortunately, official confirmation of this yet.

Conclusion

The theme of the knowledge of dreams originated long ago, but to this day the interest in it never waned. Modern science is far advanced in the study of dreams, and attempts to understand their essence no longer pass through a mystical prism. Conducted various experiments for the study of dreams themselves, the physiology of sleep, and even attempts to visualize the dreams on the screen.

The technique of lucid dreaming to solve their problems is becoming more people of different religions, ages and social status, by some experts recommended it as a way of self-awareness and resolve internal, psychological problems.

Despite this, there are still studies and practices, trying to unravel the symbolism of dreams for their own purposes.
Not spared the theme of dreams and explorers NOF – practically every phenomenon is a hypothesis to explain its essence through dream or sleep pathologies. A good example here is the phenomenon of alien abduction. After waking up about 40 % of people at least once in my life I experienced sleep paralysis. He is sometimes accompanied by vivid, very realistic dreams, and upon awakening the person may be paralysed from a few seconds up to 2 minutes. Among the subjects sleep may be aliens. Very realistic sleep paralysis and can produce in susceptible individuals a strong effect – and they are, sincerely believing this, I can tell other people that they were abducted by aliens.

Thus, for the study of interesting physiological mechanisms of sleep and dreaming, but also phenomena connected with them.

On this topic you can read:

• Stephen LaBerge, Lucid Dreaming: Psychophysiological Studies of Consciousness during REM Sleep (Lectures)
• Alexandrov, Y. I. Psychophysiology: textbook for universities. SPb.: Peter press, 2003 (in particular Chapter 13. Sleep and dreams)
• E. R. Dodds. The dream images and the images of culture // Dodds E. R. the Greeks and the irrational. SPb., 2000, pp. 152-197.
• http://ldreams.ru/category/avtoryi/ (list of books)
• http://www.sleep.ru/lib/index.htm (list of books)
• http://www.membrana.ru/particle/16803

Take out thanks to Olga-X

Translated by «Yandex.Translator»