The science of sleep cannot boast of its significant age. In essence, the research of the brainwork by scientists continues only the last hundred years. Have you ever tried to do without sleep for a week or a month? Clearly, it is almost impossible. After some time, our brain is tired. The body starts to ache. People without sleep become irritable, lose the ability to think clearly and cannot concentrate. They need sleep - time to recuperate and stockpile for the next activity.
People over 20 years out of 60 spends in a dream, and that is one third of all life. People deprived of sleep die within 10-12 days (Wegner, Wenzlaff & Kozak, 2004). Insomnia is very painful, and not by chance in ancient China, there was a sentence to death sleep deprivation.
In modern life, there are many harmful factors affecting the organism: violation of ecology, the rapid pace of life, poor diet, constant stress, an abnormality of the day. Under their influence, a person feels depressed, his mind deteriorates, health level decreases. Fast pace of life does not allow people to fully take care of their health. Often due to lack of time, we break to sleep, which has quite a detrimental effect on the body.
The youth of today has quite unconscious attitude to the health. They violate the dream regime, sleep hygiene. The result is that young people are getting nervous, not attentive, irritable, not even suspecting the cause of this. The main reasons for this is sitting too long over lessons, computer, television, pastime in nightclubs, improper diet, internal experiences, etc.
For school-age children, sleep is one of the important parts of life. During sleep, all the information obtained during training is digested and processed by the brain. Kids more than anyone else need sleep and rest. Therefore, it is useful for students to take 30-40 minutes sleep after school. No wonder there are kindergartens naps.
It is necessary to pay attention to the fact that sleep disorders lead to disruptions in the body. After all, most people do not think about it because pace of modern life does not permit. People spend most of their time working, satisfying their needs, but not their health. Modern people do not properly care about themselves, hoping for doctors, but it is better not to forget that the initial health never returns. I would like people to rethink their relationship to their own health, and take care of themselves and others.
Sleep is a natural physiological process of staying in a state with a minimum level of brain activity and reduced response to the world, or a general inhibition. Physiologically normal sleep is different from other similar to it states - hypnotic sleep, coma, fainting, lethargy (Fantini et al., 2005). This condition is necessary for every living creature. It has been studied for many years, but so far, scientists have failed to understand the purpose of sleep, despite the fact that for many decades, they conducted various experiments on humans and animals. Before bedtime there comes drowsiness - falling asleep, during which there is a decrease in brain activity. It is characterized by a decrease in the level of consciousness, yawning, reduced sensitivity, heart rate becomes slower, etc.
During sleep in a state of complete rest there increases the level of anabolic processes. Onset of sleep also depends on the lighting of the day and the room where we sleep. Toward evening, the human body begins to produce the hormone melatonin. Increasing levels of the hormone causes us an irresistible desire to sleep.
We fall asleep due to melatonin. This hormone is produced in the brain at nightfall. With the development of science there were formed various theories about sleep. Some have argued that sleep is called "bleeding of the brain." But the nature of sleep was better explained by Pavlov. Reflections on the causes of sleep occurred to him under the influence of random observations in the laboratory. Dog prepared for the next experience. It stood a long time in the machine and went to sleep, hanging straps. No stimuli could get it out of this state. There followed special experiments and research. As a result, the researchers concluded that sleep is a general inhibition. It covers the entire cerebral cortex and even captures the midbrain.
Sleep comes when brain cells need to rest. Therefore, Pavlov called sleep protective inhibition. It is a helper of the nervous system, protecting the body from fatigue. Sleep can be induced by rhythmic stimulation: measured strokes of drops, a clock ticking, the sound of wheels of a car, monotonous song (Bischof & Bassetti, 2004). Pavlov noticed that people who do not particularly have a strong intellect, with repetitive stimulation, even when it was out of place and out of time, run into an irresistible sleepiness.
Modern science has revealed the deeper causes of sleep. Change of wakefulness and sleep is associated with the activities of the network substances of the brainstem. Cortex can suppress or maintain wakefulness. Awakening occurs only when the excitation through a network substance reaches the cortex. Sleep is not interrupted if the signals are negligible. Inhibition of cells of the reticular formation induces sleep, and their active influence on the cells of the cortex - wakefulness. Excited state of the cortex influences the reticular formation, increasing or inhibiting its activity.
The scientists found in the human body cells responsible for starting the process of falling asleep. According to New Scientist, with reference to the results of research, we are talking about astrocytes - cells that, releasing a chemical called adenosine, helping a person to sleep (Moreno, 2006). The key to deciphering the mechanism of sleep was found by an Italian researcher Tommaso Fellin and his American colleagues. According to one popular theory, during the day a person accumulates adenosine, and during sleep this substance is consumed, which was a conclusion reached by Fellin during his research.
Adenosine inhibits the neurons that normally stimulate the cerebral cortex and causes a person to be awake. Seeing that the physiological mechanisms that lead to the need to sleep, work on the principle of accumulation, the researchers decided to test whether astrocytes are a source of adenosine.
In the experiment, experts used genetically modified mice, in which there was suppressed production of adenosine from astrocytes. Without this substance they virtually stopped sleeping. At the same time, scientists noticed that their intervention abolished some of the negative effects that accompany the loss of sleep.
Thus, Fellin was able to prove that astrocytes are responsible for the accumulation of adenosine and regulation of sleep (Hobson, 2011). Scientists discovered a genetic mutation that enable carriers to reduce their sleep time without harm to the vitality that will make it possible in the future to develop techniques for the recovery of sleep disorders in humans.
Dream is a special state of consciousness of a person, which includes a number of stages, regularly repeated throughout the night. The occurrence of these stages is due to the activity of different brain structures. Separate are the two phases of sleep: slow and fast. In the phase of slow sleep the body recovers physically. In adults, this sleep occupies 75%. The entire body is resting. In the phase of deep slow sleep, the brain produces a huge amount of melatonin - the sleep hormone. But after a little time, there is the phase of quick sleep. Eyeballs move, the brain is active, but people are still deeply asleep.
Sequence of phases of sleep is preserved if a person sleeps at unusual times. Brain activity during sleep is often superior to the daily level. Sleep is not frozen unconsciousness. Scientists began to speak figuratively about "hot mind sleeping". There was fixed regular recurrence of such conditions every 80-90 minutes. This condition became known as the phase of paradoxical sleep. About 4-5 times it interrupts shallow sleep and every time lasts up to 10 minutes, before waking up – up to 30. In this phase people have dreams. What is the meaning of the paradoxical sleep, combining deep unconsciousness with increased brain activity, tachytrophism with total body relaxation? It is a paradox!
Experiments were conducted to reduce the duration of sleep and, on the contrary, increase its duration. It was suggested that astronauts could be flying in a dream state, and they will use less oxygen and food (Nir & Tononi, 2010). During sleep there is a growing brain activity, increased blood pressure, pulse quickens, increased oxygen consumption. Enhanced metabolism occurs.
At night we actively sweat, and not because it is hot under the blanket. With sweat the body cleans (per night in bed sweat is left from half a cup to two). Therefore, it is very important to sleep after a shower to wash off all the wastes of the body. In the dream, we all quickly lose the ability to see and smell - the loss of smell is very strong. In the dream, partly retained is the ability to perceive tactile and auditory stimuli. At the moment of sleep, there decreases gas exchange, lower energy consumption, blood pressure drops, less breath, calmer and less heart beats, the muscles relax.
In sleep there changes rhythm of cortex biocurrents, but they do not disappear entirely (Mancia, 2004). In some cases, areas of the brain continue strenuous activity. It is known that some of the poems of Pushkin were folded in a dream. Mendeleev argued that the periodic system was developed by him during sleep. Under the influence of a strong creative drive, the brain can work in a dream. But this happens rarely, and usually in a dream a person thinks chaotically. It is known that in case of people who were born blind the dream is not visual, but tactile, sound, smell, because their brain cells have no traces of visual impressions. During sleep, their eyes do not move, unlike sighted.
The main answer to the question why we need sleep becomes the conclusion that sleep is needed in order to live. Year after year, century after century, people have tried to understand the importance of sleep in their lives, but still its exact purpose nobody guessed. Modern professionals have several versions of this bill, but none of them has the conclusive value, only suggestive. The main assumptions of experts still remains the one that explains the dream like a state, in which there is possible destruction of the so-called "sleep factors" - certain substances that accumulate in the brains of people over a period of wakefulness. Their destruction is a rest for the brain, which, after sleep, again becomes active and capable of productive work (Frank & Benington, 2006).
However, we all know one thing - we need sleep to rest the brain and body. Maybe scientists still unravel its real purpose or modern version of the answer to the question why we need sleep. And maybe, version of wise Aristotle, two thousand years ago, saying that sleep is half way along the road to death, is the most close to the truth.
First of all, we need sleep to restore forces spent during the day by the tired bodies. During sleep, the body itself will start recovery processes, gradually bringing out of the body the substances that give us a sense of fatigue, energize muscles. In our bodies there are laid unique self-healing mechanisms that can be run in full, when we have more sleep.
It is during sleep that the old cells are removed, replaced by new ones. The diseased cells receive the necessary substances for self-healing, and in case of failure, cell just dies, and in its place, there is a new (Yu, 2006). That is, in the dream body heals itself, and without any drugs. If a person is sick or recently had an operation, he needs more time to sleep, because it is during sleep that the restoration and regeneration of tissues takes place. It is no wonder that sick person is experiencing increased sleepiness - this is a protective reflex inherent in our nature.
During sleep, the brain cells recover their capacity for work; they actively absorb nutrients and accumulate energy. Sleep restores mental strength, creating a feeling of freshness, vigor, willingness to work. It protects the brain from the surge. Dreaming is the subjective perception of images (visual, auditory, tactile and other) arising in the mind of the sleeping person. Dreamer during sleep usually does not understand that he is asleep, and perceives the dream as an objective reality.
Any person certainly dreams, but many people forget it. Often they think that dream last only seconds. But this is wrong. They continue as long as it would take real action in reality. They may extend from 8 to 30 minutes (Vertes, 2004). It has been proven that sleep is usually accompanied by dreams and dreamless sleep can lead to serious disorders. It is believed that dreams are a kind human valves to release unused nervous energy.
Why dreams are needed? One theory is that dreams occur during rearrangement of information and solving the problem in mind. But the psychologist Sigmund Freud theorized that dreams are expressed in those ideas and impulses that during wakefulness are hidden in the subconscious mind of man.
Dream life is an unprecedented combination of past experiences. In ancient times, dreams were made for the revelation of the gods. People believed that good and evil spirits can enter the body through sleep and dreams to tell them different information, to persuade them to certain actions, events portend. But even then it was noticed that in dreams, gods and spirits prefer to express clear, sometimes symbolically, empowering people themselves to solve the hidden meaning of dreams.
References
Bischof, M., & Bassetti, C. L. (2004). Total dream loss: a distinct neuropsychological dysfunction after bilateral PCA stroke. Annals of neurology, 56(4), 583-586.
Fantini, M. L., Corona, A., Clerici, S., & Ferini-Strambi, L. (2005). Aggressive dream content without daytime aggressiveness in REM sleep behavior disorder. Neurology, 65(7), 1010-1015.
Frank, M. G., & Benington, J. H. (2006). The role of sleep in memory consolidation and brain plasticity: dream or reality?. The Neuroscientist, 12(6), 477-488.
Hobson, J. A. (2011). Dream life: An experimental memoir. MIT Press.
Mancia, M. (2004). The dream between neuroscience and psychoanalysis. Archives italiennes de biologie, 142(4), 525-531.
Moreno, J. D. (2006). Mind wars: Brain research and national defense (pp. 177-178). Washington, DC: Dana Press.
Nir, Y., & Tononi, G. (2010). Dreaming and the brain: from phenomenology to neurophysiology. Trends in cognitive sciences, 14(2), 88-100.
Vertes, R. P. (2004). Memory consolidation in sleep: dream or reality. Neuron, 44(1), 135-148.
Wegner, D. M., Wenzlaff, R. M., & Kozak, M. (2004). Dream Rebound The Return of Suppressed Thoughts in Dreams. Psychological Science, 15(4), 232-236.
Yu, C. K. C. (2006). Memory loss is not equal to loss of dream experience: A clinicoanatomical study of dreaming in patients with posterior brain lesions. Neuropsychoanalysis, 8(2), 191-198.
