(ORDO NEWS) — If sleep is a natural phenomenon that evolution has worked for billions of years, why are so many people suffering from insomnia? How important is sleep to our physical and mental health? What exactly happens in a dream and why?
Almost every night we experience a striking metamorphosis.
According to National Geographic article published on May 21, the brain completely changes its behavior and goals, dimming consciousness. For a while we find ourselves almost paralyzed. However, from time to time, our eyes rush behind closed eyelids, as if we are seeing something, and the tiny muscles of the middle ear, even in silence, are tensed as if we are hearing something. We all, both men and women, experience sexual arousal, and more than once. Sometimes it seems like we are flying. We are approaching the borders of death … We are sleeping.
Around 350 BC, Aristotle, reflecting on what exactly happens in a dream and why, wrote a treatise on Sleep and Wakefulness. For the next 2300 years, the questions of the Greek philosopher remained unanswered until, in 1924, the German psychiatrist Hans Berger invented the electroencephalograph, a device that records the electrical activity of the brain. And then the study of sleep passed into the field of natural sciences. But only in recent decades, tomography allowed us to take a closer look at the processes taking place in the sleeping brain, and we came closer to giving an answer to Aristotle.
Everything we learned about sleep confirmed the importance of this condition for our mental and physical health. The sleep and wake cycle, one of the most important features of human biology, helped to adapt to life on a rotating planet with its endless change of day and night. It is no accident that the 2017 Nobel Prize in medicine was awarded to three scientists who in the 1980–1990s discovered “molecular clocks” in our cells that are responsible for synchronizing the human body with the sun. When this circadian rhythm breaks, we have serious problems – diabetes, problems in the cardiovascular system and early senile dementia.
Meanwhile, the imbalance between lifestyle and the solar cycle has become epidemic-wide. “It’s as if we live inside a global experiment to study the negative effects of lack of sleep,” notes Robert Stickgold, director of the Sleep and Thinking Center at Harvard Medical School.
The average American today sleeps less than seven hours a day – a couple of hours less than a century ago. This is mainly due to the spread of electric lighting, as well as televisions, computers and smartphones. And the dream is now seen only as an obstacle that impedes our activities and entertainment. Already Thomas Edison, the inventor of the bulb, said: “Sleep is absurdity, a bad habit.”
A full night’s sleep now seems old-fashioned, like a hand-written letter. And we all are hunting, fighting: sleeping pills, yawning – horse doses of coffee. And we avoid that amazing journey that we must go every evening to go through several stages of sleep four or five times a night, each of which has its own characteristics and functions.
When we fall asleep, the brain remains active and starts the process of “editing” – it decides which memories to keep and which to discard.
Immersion in sleep occurs quickly. The human body does not like to be in an intermediate state, lingering “in the doorway”. It is better to be either here or there, awake or sleeping. Therefore, we turn off the light, go to bed and close our eyes. If the circadian rhythm is tied to the alternation of daylight and darkness, and the pineal gland at the base of the brain releases melatonin, signaling that night has come, and if many other body systems work smoothly, then neurons quickly fall into sleep.
When we are awake, neurons – and there are about 86 billion of them – are like a randomly rushing crowd, like a cell storm. When they work evenly and rhythmically, the waves on the electroencephalogram (EEG) run in even rows, and this indicates that the brain has “gone into itself”, away from the chaos of waking life. At the same time, our sensitivity weakens, and soon we fall asleep.
Scientists call this stage the first stage, a coastal shallow bed of sleep. It lasts about five minutes. Then, in the depths of the brain, a series of electric flashes arise, which rush to the cortex – the outer shell of the brain responsible for language and consciousness. These half-second flashes – sigma-rhythms, or sleep spindles, indicate that the second stage has come. However, the brain does not become less active, as was believed for a long time: just its activity takes on a different character. Theoretically, sigma rhythms stimulate the cortex in such a way as to preserve recently acquired information, and possibly to connect it with existing knowledge in long-term memory. When people face new mental or physical challenges in sleep labs, the frequency of their sigma rhythms increases the next night. And it seems that the more sigma rhythms arise.
Some experts have suggested that the intensity of nocturnal sigma rhythms may even serve as an indicator of the general level of intelligence. Sleep in the literal sense of the word creates bonds that you might never consciously form. It is no coincidence that they say that the morning of the evening is wiser.
The waking brain is adapted for collecting information, the sleeping one for processing it. In other words, at night we switch from “recording” to “editing”, and it is the sleeping brain that decides which memories need to be saved and which ones to delete. And selection is not always in favor of the most necessary. Sleep enhances memory – not only in the second stage, but throughout the night cycle. Therefore, for example, soldiers exhausted by fierce battles, it would be better not to go to bed immediately after the battle. To prevent post-traumatic stress disorder, soldiers should continue to stay awake for six to eight hours, according to neuroscientist Gina Poe of the University of California, Los Angeles. Studies by her and other scientists show that if a person goes to bed shortly after a difficult event without first trying to comprehend what happened.
The second stage lasts up to 50 minutes during the first 90 minute sleep cycle. (In other cycles, less.) At first, sigma rhythms occur every few seconds, then their frequency decreases, and the heart rate slows down. Body temperature drops. Perception of the outside world is lost. A long dive begins in the third and fourth stages of sleep.
We enter a deep, coma-like dream that the brain needs just as much as the body needs food. This time is for “physiological cleaning”, not for daydreaming.
Without exception, all animals sleep, even if their sleep takes on unusual forms. Three-fingered sloths spend about ten hours a day in a dream, which already seems to us an excessive manifestation of apathy, but this is not the limit: some fruit-eating bats manage to doze for 15 hours, and of these, a small brown night-night lounges all 20. Giraffes sleep less than five hours. Horses spend midnight standing, and half lying. Dolphins sleep one hemisphere while the other is awake, which allows them to swim without stopping. Large frigates and other birds are able to doze in flight. Nanny sharks are resting, gathering in a pile at the bottom of the ocean. Cockroaches lower their mustache while they sleep, and they, like us, are sensitive to caffeine.
During sleep, all reactions weaken and mobility is reduced even in animals that do not have a brain at all. When jellyfish sleep, the pulsation of their bodies slows down, and unicellular organisms, such as yeast, show clear cycles of activity and rest. This means that a dream is an ancient phenomenon, a law of nature, and its initial and universal function is not to organize memories or stimulate learning, but to preserve life itself. Obviously, any creature, regardless of size, cannot remain active around the clock. “Staying awake requires a lot of effort,” says Thomas Scammell, professor of neurology at Harvard Medical School. “After all, you have to constantly compete with other organisms in order to survive, and, accordingly, a period of rest is needed to help cells recover.”
In humans, this occurs mainly during deep sleep, at the third and fourth stages, which differ from each other in the level of brain activity, consisting, as the EEG shows, of large cyclic delta waves. In the third stage, delta waves are less than half the time; in the fourth – more than half. During deep sleep, our cells produce most of the growth hormones necessary throughout life for the functioning of bones and muscles.
There is other evidence that sleep is vital for maintaining a healthy immune system, body temperature, and blood pressure. If sleep is not enough, we cannot successfully control our mood or recover quickly from injuries. Perhaps sleep is more important to us than food; animals deprived of sleep die faster than from starvation, says Stephen Lockley, a doctor at the Brigham and Women’s Hospital Center for Medicine.
Apparently, a good dream also reduces the risk of developing dementia. A study in mice by Miken Nedergaard of the University of Rochester in New York shows that when we are awake, neurons are tightly packed together, but during sleep, some brain cells contract by 60 percent and the gaps between them widen. These intercellular spaces are a place of discharge of metabolic waste products of cells, in particular the beta-amyloid peptide, which destroys the connections between neurons and affects the development of Alzheimer’s disease. Only during sleep, cerebrospinal fluid passes, like a detergent, through these wide corridors of our brain, washing out amyloid beta.
As long as all these “cleansing and repairing works” take place, the muscles are completely relaxed. Mental activity is minimal: waves of the fourth stage on the EEG look like in patients in a coma. Usually at this time we do not see dreams and may not even feel pain. In ancient Greek mythology, the gods Hypnos (dream) and Thanatos (death) are twin brothers. Perhaps the Greeks were right. “We are dealing with a very deep level of brain deactivation,” explains Michael Perlis, director of the Behavioral Sleep Medicine program at the University of Pennsylvania. – Sleep in the fourth stage is not much different from coma or brain death. This condition helps to restore and strengthen forces – but staying in it for a long time, pouring it is also harmful.”
Most often, we stay at this stage for about 30 minutes, and then the brain breaks out of it. (This shift may be accompanied by a sharp convulsive movement – at least in sleepwalkers). After that, we often go through the third, second and first stages – and wake up. Even people who do not have sleep disorders wake up several times a night, although most do not notice this: we fall asleep again in a matter of seconds. But at this stage, instead of repeating the stages, the brain changes the program and sets off on a new, truly strange journey.
According to the Centers for Disease Control and Prevention in the United States, more than 80 million adult Americans are chronically sleep deprived, that is, they sleep less than the recommended minimum of seven hours a day. Over a million accidents on the roads and many medical errors occur annually due to fatigue. Even small changes in sleep patterns can cause problems: on the first Monday after daylight saving time, compared to other Mondays, the number of heart attacks in America rises by 24 percent and the number of fatal accidents rises sharply.
During our lives, about a third of us experience at least one diagnosed sleep disorder: from chronic insomnia and respiratory arrest attacks to restless legs syndrome (an irresistible desire to constantly move our limbs) and more rare and strange disorders. So, narcolepsy – uncontrolled attacks of sudden falling asleep – is often caused by strong positive emotions when, for example, a person listens to a funny story or tastes delicious food. People with Kleine-Levin syndrome sleep every few years almost without interruption for a week or two (and return to normal life without noticeable side effects). And sleep paralysis (the inability to move in the first few minutes after waking up), as shown by studies at Harvard University, has generated many stories about the abduction of people by aliens.
Insomnia is by far the most common problem today that forces many adults (4% in the US) to take sleeping pills. As a rule, sufferers of insomnia need more time to fall asleep, or they wake up at night, or face both of these problems. If sleep is such a universal natural phenomenon that evolution has worked for billions of years, then why are so many people tormented by it? You can blame evolution, life in the modern world – or the discrepancy between them.
Anyone sleeping less than six hours a day has a tendency to depression, psychosis, stroke, and obesity. Insomnia weakens the entire body.
Evolution has endowed us, like other creatures, with a dream that can be adjusted in time and is easily interrupted in case of danger: say, if a child is crying nearby or the steps of a predator are approaching. The brain can quickly switch from “autopilot” to a “manual control” system that will wake us up in an emergency.
However, in the modern world, an ancient, innate readiness for awakening constantly works in situations that do not threaten life, such as anxiety before an exam or worries due to lack of money. Before the industrial revolution, which gave us alarms and a fixed work schedule, people often could counteract insomnia by simply sleeping longer in the morning. Now there is no such possibility. And if you are one of those who are proud of the ability to quickly fall asleep almost anywhere, then it is better not to brag – this is a sign of acute lack of sleep, especially if you are not yet forty.
The brain segment, the first to suffer from lack of sleep, is the prefrontal cortex, which is responsible for making decisions and finding a way out of difficult situations. Sleeping people are more irritable, moody and irrational. “Apparently, lack of sleep to some extent affects all cognitive functions of the brain,” said Chiara Cirelli, a neuroscientist at the Wisconsin Institute of Sleep and Consciousness. It is known that people who have not slept in the police are ready to admit any accusations in exchange for sleep.
Everyone sleeping less than six hours a day has a tendency to depression, psychosis, and stroke. Lack of sleep is also directly related to obesity: without enough rest in the body, ghrelin, the “hunger hormone” is produced in excess, which makes a person eat more than necessary. To prove a causal relationship in such cases is a difficult task, since the necessary experiments for this cannot be carried out in humans. But it is clear that insomnia weakens the entire body.
Afternoon sleep does not solve the problem; medications do not solve it. “Sleep is not homogeneous,” explains Jeffrey Ellenbogen, a somnologist at Johns Hopkins University who advises companies on the relationship between high performance and healthy employees. – Sleep is not a marathon; it looks more like a decathlon. The idea of manipulating sleep with drugs and devices seems tempting, but we still don’t know enough about this process to try to artificially control it – it’s too risky.”
Of course, if we could just undo unnecessary parts of sleep, it would add several decades to our conscious life. At the dawn of somnology, in the 1930s – 1940s, some scientists even believed that the second half of the night was useless for relaxation, and you could not sleep at all at this time. Later it turned out that just at this period we find ourselves in the grip of how unusual, so necessary form of sleep, which, in fact, is a special type of consciousness.
In a state of insanity, we dream, fly and fall – although we may not remember this.
Sleep with fast eye movement, or fast sleep, was discovered only in 1953 by Eugene Aserinsky and Nathaniel Kleitman from the University of Chicago. Previously, due to the lack of distinguishing features in the early EEG images, fast sleep was not given much importance, considering it a variation of the first stage. But after the characteristic eye movements and the accompanying rush of blood to the genitals were recorded, it became clear that the most vivid dreams happen just at the stage of REM sleep, and this was a breakthrough in somnology.
Typically, a healthy sleep first goes through four stages, then an instant return to wakefulness, and then five to twenty minutes of REM sleep. With each subsequent cycle, REM sleep time is approximately doubled. Somnologists believe that a certain sequence of slow and fast sleep optimizes our physical and mental recovery. At the cellular level, during REM, protein synthesis necessary for the functioning of the body is activated.
Each time, experiencing the stage of REM sleep, we literally go crazy. Psychosis is a condition characterized by hallucinations. Some somnologists say that dreams are a kind of psychosis: we are completely sure that we see what is not, and we take for granted that time, place, and even people can transform or suddenly disappear.
From ancient Greeks to fortune-tellers and Sigmund Freud – for many centuries dreams were filled with charm and shrouded in mystery, they were perceived as messages from the gods or from the subconscious. Today, many somnological experts are not interested in specific images and events in dreams, considering dreams to be the result of chaotic neural impulses. Even if they are full of emotions, then they are devoid of meaning. Only after awakening, the brain, in search of meaning, quickly “sews” the plot out of promiscuous fragments.
However, not all experts share this opinion. “The content of dreams,” says Robert Stickgold of Harvard, “is part of an evolutionary mechanism for evaluating fresh memories and their usefulness in later life.”
Even if you cannot remember a single dream, you still see them. Lack of dream memories is actually a sign of healthy sleep. Thanks to new technologies, it was possible to determine what happens at the physical and chemical levels, when we dream about something at the stage of slow sleep, but it is believed that such dreams are more like overtures to great ideas. Only during REM sleep does the full power of nighttime madness fall upon us.
Each time, experiencing the stage of REM sleep, we literally go crazy. Psychosis is a condition characterized by hallucinations. Some somnologists say that dreams are a kind of psychosis.
It is often said that dreams are instant flashes, but this is not so: they occupy almost the entire phase of REM sleep, about two hours per night, although this indicator decreases with aging – perhaps because with age our brain becomes less flexible, learns during wakefulness is worse and receives less information to process during sleep. Newborn babies sleep up to 17 hours a day and spend about half of this time in a state similar to a quick sleep. And about a month in the womb (probably from the 26th week of pregnancy), the fetus is in a state very similar to fast sleep. It is believed that all the time spent in a state of REM sleep is something like testing software for the brain, preparing for a full-scale launch. This process is called corticalization of functions. And this is nothing more than the activation of the mind.
Body temperature during REM sleep remains at the lowest level. The heart rate, in comparison with other stages of sleep, becomes more frequent. Muscles, with a few exceptions – eyes, ears, heart, diaphragm – are immobilized. Unfortunately, this does not stop some snoring: this curse for a bedmate (and the reason for creating hundreds of devices against snoring) is caused by the turbulent flow of air vibrating in the relaxed tissues of the throat or nose. During REM sleep, our ability to react to stimuli completely disappears, and our mouth may involuntarily open. Nevertheless, the brain is able to convince us that we ride in the clouds or fight dragons.
Belief in the unbelievable is explained by the fact that during REM, logical centers and areas of self-control are almost disconnected. The production of two special substances, serotonin and norepinephrine, completely stops. Since these neurotransmitters allow brain cells to communicate, and without them, our ability to learn and remember new information would be severely impaired, we find ourselves in a state of chemically altered consciousness. At the same time, the brain is fully active, absorbing as much energy as during the wakeful period.
The limbic system , the wild jungle of the mind , where some of the basic instincts arise, governs fast sleep . Freud was right, dreams really correlate with our primitive emotions – sex drive, aggression and fear, but also with delight, joy and love. Although it seems like we have more nightmares than good dreams, this is most likely not true. Nightmares are simply more likely to trigger a system of rapid brain awakening.
During REM sleep, the varolium bridge is especially active – a roller-like part of the stem brain. Electrical impulses from the Varoliev bridge are often directed to the part of the brain that controls the muscles of the eyes, so the eyeballs quickly turn from side to side, although the eyelids remain closed. The same can be said about those areas of the brain that are responsible for movement, so in a dream there is often a feeling of flying or falling. We see color dreams if we are not blind from birth, and in this case, dreams have no visual images, but remain emotionally saturated. Male and female dreams appear to be emotionally similar. Every time a man sees a dream, even if he is not erotic, he has an erection; in women, the blood vessels in the vagina become saturated with blood. And while we sleep, no matter how absurd our dreams are, we are almost always convinced that we are awake. In man’s head is the greatest virtual reality machine.
The end of REM sleep is usually marked by a brief awakening. If we wake up naturally, without an alarm, the last dream often ends the rest. And daylight helps awakening: when light seeps through the eyelids and reaches the retina, a signal is sent to the deepest region of the brain – the suprachiasmatic core (SCN), and we open our eyes and return to real life.
Or not? Perhaps the most remarkable thing about fast sleep is that the brain can work regardless of the presence or absence of external stimuli. As an artist, settled in a secret studio. In a dream, more precisely in the first period of REM sleep, the most complex and perfect tool known to the world is free to do and see what it wants. For the brain, it can be said, the time of games. Some scholars believe that it is during the REM stage that we become especially intelligent, insightful, creative, and free. Sleep is the time when we truly live.
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