The impact of sleep and dreams on our lives
Our brain fundamentally changes its behavior and functions, muffling consciousness. For some time we are almost completely paralyzed: we do not even shiver from the cold. But the eyes under the eyelids periodically twitch, as if they see something, and the tiny muscles in the middle ear, even in complete silence, move as if they hear something. From time to time we (that men, that women) are sexually excited. Sometimes there is a feeling of flight. We are at the very borders of “death.” We are sleeping.
Around 350 BC. er Aristotle wondered what we were doing in this state and why. Over the next 2300 years, no one has managed to give an intelligible answer. In 1924, the German psychiatrist Hans Berger invented a device that records the electrical activity of the brain, and the study of sleep passed from the field of philosophy to the field of science. But we managed to get closer to convincing answers to Aristotle’s questions only in the last few decades when neuroimaging devices allowed us to get a more detailed view of the internal mechanisms of the brain.
Everything that we managed to learn about a dream underlines its importance for our mental and physical health. The alternation of sleep and wakefulness is a central feature of human biology, an adaptation to life on a rotating planet, to an endless cycle of day and night.
In 2017, the Nobel Prize in Medicine was awarded to three scientists who in the 1980s and 1990s found molecular clocks in our cells that synchronize the rhythms of the body with the time of day. As shown by recent studies, with circadian rhythm disturbances, the risk of diabetes, cardiovascular diseases and dementia increases.
At the same time, the discrepancy between the modern lifestyle and the alternation of day and night has become the scale of the epidemic. “We seem to live within the framework of a worldwide experiment to study the negative effects of sleep deprivation,” said Robert Stickgold, director of the Center for the Study of Sleep and Cognitive Abilities at Harvard Medical School. Today, the average American sleeps less than 7 hours a day – almost 2 hours less than in the last century. For the most part, this is due to the proliferation of light bulbs, and later – televisions, computers, and smartphones. Our restless society, accustomed to life in the ocean of artificial light, often perceives sleep as an adversary – as a condition that deprives of productivity and the possibility of having fun. Thomas Edison, who brought light bulbs into our lives, called sleep a nonsense and a bad habit. He believed that in time we could finally get rid of him.
A full night’s sleep is now considered to be something exceptionally rare and old-fashioned as writing, written by hand. We always cheat: fighting insomnia with sleeping pills whip coffee to stop to yawn, strongly shirk intricate journey, in which, on idea, should go every night. If sleep will be able to fame, we have 4-5 times to pass through several stages of sleep, each of which has clearly defined properties and the assignment is winding, a real transition to a parallel world.
The first and second stages
When we fall asleep, the brain remains active and processes the memories: decides which ones to save and which ones to get rid of.
Transformation begins very quickly. The human body does not like to stomp in the passage between the two states. We prefer to stay in one thing: either to be awake or to sleep. And here we turn off the light, go to bed, close our eyes. If the circadian rhythm is reliably tied to the time of day, if the epiphysis produces melatonin, signaling nightfall, and if a number of other systems obey his instructions, our neurons will immediately begin to work in a single rhythm.
Neurons (there are about 86 billion) are cells that form in the brain an analogue of the World Wide Web, interacting with each other through electrical and chemical signals. When we are awake, the neurons resemble a noisy crowd: a real storm is raging in the brain. And when they are activated evenly and rhythmically (on the electroencephalogram (EEG) this is evident in a slender ripple), this means that the brain has switched to internal tasks, moving away from the chaos of everyday life. At the same time, the activity of sensory receptors is muffled, and soon we fall asleep.
Scientists call this period the first stage, the “shallow water” of sleep. It lasts about 5 minutes. Then from the depths of the brain comes a series of electrical impulses that spread through the cortex of the big hemispheres – folded gray matter, covering the outer layer of the brain (it is responsible for speech and consciousness). These half-second flashes are called sleepy spindles (or sigma-rhythms) and they mark the beginning of the second stage.
Brain activity in a dream does not decrease, as scientists have believed for a long time – its activity is simply manifested differently. In theory, sleepy spindles stimulate the bark to retain fresh information – and, perhaps, help to link it with the knowledge already in long-term memory. During experiments on the study of sleep, when people were asked to perform new tasks for them of mental or physical nature, the frequency of appearance of sigma rhythms increased. Apparently, the more spindles were fixed, the better the subjects were able to complete the task the next day.
According to some experts, in terms of the frequency of nightly sigma rhythms, you can even get an idea of the level of mental development. In a dream, connections are created that could hardly have been formed consciously, and we all intuitively guess this.
Awake brain is best suited for collecting external signals, the brain is asleep – to consolidate the information received. At night, we switch from “record” to “montage”: this can be traced at the molecular level. We are not just mechanically sorting thoughts – the sleeping brain actively selects which memories to leave, and which ones to get rid of.
The brain does not always make wise choices. Sleep powerfully activates the memory: not only in the second stage, in which we spend almost half of our sleep, but also throughout our looped back journey. Therefore, for example, it would make sense for fatigued soldiers not to go to bed immediately after returning from tasks that are difficult for the psyche. According to neuroscientist Gina Po, from the University of California, to prevent the occurrence of post-traumatic disorder, soldiers need to stay awake for another 6-8 hours. A study conducted by her and her colleagues showed that going to sleep immediately after a serious incident, before the brain can at least partially cope with emotions, is likely to turn the experienced into a long-term memory.
The second stage can last up to 50 minutes in the first 90-minute cycle during the night (its share in the subsequent cycles is less). Sigma rhythms may appear for a while every few seconds, but then the impulses become less frequent. Heartbeat slows down. Low body temperature. The last signs of awareness of what is happening around are disappearing. We begin a long dive to the third and fourth stages – into the depths of sleep.
Third and fourth stages
We fall into a deep, coma-like sleep that our brain needs as much as our body needs food. This time is not intended for dreams, but for physiological cleaning.
Sleep – even in a primitive form – is found in all animals, without exception. The three-toed sloths doze for about 10 hours a day, which already seems a depressing manifestation of apathy, but some of the Wings can spend up to fifteen hours in the kingdom of Morpheus, and up to twenty bats of the kind of night. Giraffes sleep less than five hours a day. Horses usually sleep part of the night standing, and part of it lies down. Dolphins sleep in hemispheres: while one half of the brain is asleep, the other is awake – this allows them to be constantly in motion. Large frigates can take a nap during the flight, and many other birds too. Nanny sharks sleep in groups, laid down on the seabed. Cockroaches in a dream fold antennas, and they are also sensitive to caffeine.
Sleep as a condition characterized by a decrease in reaction and limited mobility, which (unlike hibernation or coma) is easily interrupted, is observed even in creatures that do not possess a brain. Jellyfish can sleep: the body pulsation noticeably slows down, and in single-celled organisms (plankton and yeast fungi), cycles of activity and rest are clearly distinguished. These observations suggest that sleep is an ancient phenomenon, the original and universal function of which is not to reorganize memories and not to assimilate new material, but rather to maintain life as such. Obviously, any creature, regardless of size, cannot function continuously 24 hours a day.
“Waking is an energy consuming state,” explains Thomas Scammell, a professor of neurology at Harvard Medical School. – You need to get up and go to win all the others in the struggle for survival. One of the consequences is the need for a rest period for cell repair. ”
In humans, this occurs mainly during deep sleep, in the third and fourth stages: they differ in the percentage ratio of brain activity, which in the EEG is represented by large, sloping delta waves. In the third stage, delta waves are present in less than half of its duration, in the fourth stage, more than half. Some scientists believe that together they constitute a single stage of deep sleep. At this time, our cells produce the most growth hormone that is needed for the development of bones and muscles throughout life.
There is an impressive body of evidence that confirms that sleep is essential to maintaining a healthy immune system, body temperature, and blood pressure. In conditions of lack of sleep, we are worse able to manage our mood, and the body copes with injuries longer. Perhaps sleep is even more important than food: according to Stephen Lockle of Brigham and Women’s Hospital, animals die of sleep deprivation, and animals die faster than starvation.
There is an assumption that when we are awake, the neurons closely adjoin each other, and when we sleep, some brain cells decrease in size by 60%, thereby expanding the spaces between them. These spaces serve as a dumping ground for metabolic waste: in particular, a substance called beta-amyloid, which disrupts the interaction between neurons and is closely related to Alzheimer’s disease. And only in a dream, like a detergent, cerebrospinal fluid washes away beta-amyloid from these expanded “passages”.
While “cleaning and repair” occurs in the brain, our muscles are completely relaxed. Mental activity is at a minimum level: waves of the fourth stage are identical to the state of the brain of comatos. In the fourth stage, we usually do not see dreams. We may not even be able to feel pain. In Greek mythology, the gods Hypnos (personification of sleep) and Thanatos (personification of death) – twin brothers. It is likely that the Greeks were right.
“This is a large-scale decontamination,” explains Michael Perlis, director of the program on behavioral sleep medicine at the University of Pennsylvania. – The fourth stage is not very different from coma or brain death. Despite its restorative and strengthening properties, it is better not to abuse it. ”
We can stay in the fourth stage for no more than 30 minutes, after which the brain breaks out of it. In lunatics, this moment can be accompanied by a sharp start. After that we go through the previous three stages in the reverse order and wake up.
Even healthy people wake up several times a night – although most people don’t even notice. We fall asleep again after a few seconds. However, this time, instead of going through all the stages again, the brain launches a completely new process and sets off on a journey to things that are truly out of place.
According to the Centers for Disease Control and Prevention, more than 80 million American adults suffer from chronic lack of sleep, that is, they sleep less than the recommended minimum of 7 hours. Fatigue is the cause of more than a million car accidents per year, as well as a significant number of medical errors. Even minor changes in the daily routine can lead to negative consequences. On Mondays, after the transition to winter time, the number of heart attacks increased by 24% in the US compared to regular Mondays, as well as an increase in fatal accidents.
About a third of us will face diagnosed sleep disorders at least once in a lifetime. These include chronic insomnia, temporary cessation of breathing (sleep apnea), restless leg syndrome, and other, more rare and bizarre diseases.
When people suffering from the syndrome of an exploding head try to fall asleep, it seems to them that there are sounds of explosions in the brain. A study at Harvard helped to establish that drowsy paralysis — the inability to move for a few minutes after waking — is the basis of many stories about alien abduction. People with Kleine-Levine syndrome sleep every few years for a week or two. Then the cycle returns to normal without noticeable side effects.
Insomnia is most common. It’s because of her that every single month, 4% of American adults take sleeping pills. People who are prone to insomnia usually spend more time falling asleep, or wake up at night for long periods of time, or suffer from both. If a dream is a universal natural phenomenon that has been perfected for thousands of years, the question arises: why do so many people have problems with it? Blame the evolution. The conditions of modern life are also to blame. Or rather the discrepancy between the first and second.
Like other animals, evolution has given us a dream that can be corrected in time and which can be easily interrupted: in this way they can be sacrificed in favor of higher priorities. At all stages of sleep in the brain, an emergency control system is functioning that will wake us up in an emergency: say, hearing a baby cry or the steps of an approaching predator.
The problem is that in the modern world, our ancient, innate emergency wake-up system constantly makes a false alarm because of situations that do not threaten life: worries before an exam, worries about financial situation or reacts to the sound of a car alarm. Before the industrial revolution – which gave us alarms and a clear work schedule – insomnia could often be overcome simply by sleeping. More so do not work. And if you belong to the number of people who are proud of their ability to quickly fall asleep almost anywhere, do not flatter yourself: this is a sure sign that you are not sleeping enough (especially if you are not yet forty).
First, when lack of sleep, the prefrontal cortex, the decision-making center and the search for answers to the assigned tasks, begin to fail. People who lack sleep are more irritable, subject to mood changes and irrational. “It seems that lack of sleep has a negative effect on all cognitive functions,” said Chiara Chirelli, a neuroscientist at the Wisconsin Institute for the Study of Sleep and Consciousness. Studies show that sleepy suspects in exchange for a dream are ready to admit anything.
Those who sleep regularly for less than 6 hours a day are at increased risk of depression, psychosis and stroke. Lack of sleep is directly related to obesity: if a person does not get enough sleep, the body and other organs produce too much of the hunger hormone ghrelin, which is why you want to eat more than you need. But it is difficult to establish a causal relationship, because the necessary experiments cannot be carried out in humans. However, it is obvious that lack of sleep has a negative effect on the entire body.
The problem is not solved neither “microsonic” nor a tablet. “Sleep is not homogeneous,” explains Jeffrey Ellenbogen, sleep specialist at Johns Hopkins University, who leads the Sleeping Sleep project, in which scientists advise companies on how their employees can achieve greater productivity through a more reasonable approach to sleep. “Sleep is not a marathon, but rather a decathlon. In the dream, there are many processes. Attempting to manipulate sleep with the help of tablets or special devices looks tempting, but we are not sufficiently versed in this phenomenon to take a risk and artificially change its components.”
Many experts oppose the reduction of sleep time, and especially against beliefs that appeared first: that without sleep, you can do really. The idea was great: to get rid of the breaks on unnecessary sleep, and add to the life of tens of years. In the period of sleep medicine (1930s and 1940s), many thought the second half of the night the most boring part of the holiday. Some people thought that it does not need.
It appears, however, that this period is a time for a special, but no less important forms of sleep, which in fact is another type of consciousness.
REM sleep phase
We find ourselves in a state of psychosis, in which we see dreams, fly and fall – even if we do not remember. Moreover, our mood is regulated and our memories are fixed.
The REM sleep phase (paradoxical REM sleep, REM sleep) was discovered in 1953 by Eugene Aserinski and Nathaniel Kleitman of the University of Chicago more than 15 years after the discovery of the first four stages. Prior to this, due to the absence of traces of this phase in early EEGs, it was usually considered a variation of the first stage — and not the most significant one. However, after the sharp movements of the eyes and the rush of blood to the genitals were recorded during this period, the scientific community realized that almost all colorful dreams occur at this stage. This led to a breakthrough in somnology.
As a rule, healthy sleep begins like this: a measured transition to the fourth stage, a fleeting awakening, and then a phase of fast sleep lasting from 5 to 20 minutes. With each subsequent cycle, the duration of the sleep phase is doubled. In total, it takes about? sleep adults. Nevertheless, the first to fourth stages in English are called non-REM sleep, “the phase without fast eye movement”: 80% of sleep is obtained due to the remaining 20% (the term “slow sleep phase” is adopted in Russian). Experts believe that changing slow to fast sleep somehow helps to optimize the process of our physical and mental recovery. At the cellular level in the phase of fast sleep, peak values of protein synthesis are observed, which allows you to maintain normal functioning of the body. Apparently, fast sleep is also extremely important for regulating mood and fixing memories.
Getting into the phase of REM sleep, we literally go crazy every time. A condition that is characterized by hallucinations and delusions is called psychosis. According to a number of experts, dreams belong precisely to such states: we are absolutely convinced that we see what actually does not exist, and we take for granted that time, place and people themselves can change and disappear without warning.
Mankind – that the ancient Greeks, that the interpreters of dreams, that Sigmund Freud – always considered dreams as a source of witchcraft and secrets: they were perceived as messages not from the gods, not from the subconscious. Today, many somnologists are not interested in the specific images and events from our dreams. They are convinced that dreams are the result of the chaotic activation of neurons and, even if filled with emotions, are meaningless. Just waking up, the consciousness, in search of an explanation, hastily stitches together a single piece of scattered flaps.
Other experts categorically disagree with this statement. “The content of dreams,” explains Stikgold of Harvard, “is part of an innate mechanism whose task is to analyze the significance of new memories in a wide context and their possible future benefits.”
Even if you never manage to remember dreams, you still see them. Dreams see everything. The inability to memorize them is the hallmark of a person who has no problems sleeping. Activity during dreams occurs in the deep areas of the brain, which does not clearly capture it on the EEG. However, thanks to new technologies, we were able to get an idea of what is happening – both from a physical and chemical point of view. Dreams occur in the phase of slow sleep (in particular, in the second stage), but they are considered more like overtures to the main action. Only during fast sleep do we encounter all the power of our own night madness.
Dreams are often mistakenly perceived as single-step flashes of images, but in fact they cover the entire phase of REM sleep (a total of two hours). The duration of dreams decreases with age – perhaps because during wakefulness the less plastic brain absorbs less information and, therefore, in a dream it has to process less new memories. Newborns sleep up to 17 hours a day and almost half of this time is spent in an active state, reminiscent of REM sleep. In similar conditions for almost a month, starting from the 26th week of pregnancy, the embryo is located. In theory, it’s like software testing before a full-scale launch. This process is called telencephalization. It is at this moment that a person has a mind.
In the phase of REM sleep, there is no thermoregulation in the body. Body temperature remains at the lowest possible values. Compared with the other stages of sleep, heartbeat quickens, and breathing becomes intermittent. The muscles, with a few exceptions (eye, ear, heart, diaphragm), are paralyzed. Unfortunately, paralysis does not interfere with snoring. The unpleasant feature of joint sleep, for the sake of which hundreds of devices were invented, is generated by the vibration created by the turbulent air flow in the relaxed tissues of the throat and nose. Snoring often occurs in the third and fourth stages. Even without snoring, lying with our mouth open in the phase of REM sleep, we are completely incapable of any physical reaction, even blood pressure is not regulated. We are, in a sense, “out of place”. With all this, the brain is able to convince us that at this moment we ride on the clouds and fight dragons.
Belief in the incredible is born in us, because in the phase of fast sleep the brain is no longer controlled by the centers responsible for logic and control of impulses. The production of two major neurotransmitters, which provide the interaction between brain cells, serotonin and norepinephrine, stops. Without them, our ability to learn and memory significantly deteriorate – we find ourselves in a chemically altered state of consciousness. However, unlike the fourth stage, this state is not like anyone. In the phase of fast sleep, the brain is active and consumes as much energy as during wakefulness.
The phase of REM sleep is controlled by the limbic system – the deepest region of the brain, the undeveloped jungle of the mind, where the wildest and lowest instincts live. Freud was right: dreams involve our most primitive emotions. The limbic system is responsible for sexual desire, aggression and fear. However, it also allows you to feel the elation, joy and love. Although sometimes it seems that we have more nightmares than pleasant dreams, most likely it is not. Dreadful dreams are simply more likely to activate the emergency control system and wake us up.
In this phase, a small seal in the brainstem works at full capacity – the pons. Electrical impulses from the pons are most often directed to the part of the brain that controls the eye and ear muscles. The eyelids usually remain closed, but the eyeballs move from side to side. Perhaps it depends on the intensity of events in the dream. The inner ear during dreams is also active.
The areas of the brain responsible for movement are also active, which is why we often experience the sensation of flying or falling in a dream. We see colorful dreams – unless blind from birth: in this case, there is no visual component in dreams, but emotional intensity remains. The dreams of men and women are similar in emotional content. When a man has a dream, even if its content is not related to sex, he will have an erection. In women, blood flow to the vagina is activated. While we are dreaming, we are almost always convinced that we are awake – despite the absurdity of the plot and any violations of the laws of physics. Our brain is the most perfect device of virtual reality.
Fortunately, we are still in sleep. When we see a dream, the brain tries to reproduce all the movements, but one of the systems in the brainstem completely blocks the way for signals from the motor neurons. The number of sleep anomalies affecting the nervous system (parasomnias), includes the so-called behavior disorder in the phase of rapid sleep. It is not possible to completely block motor signals, and people live through sleep events in the most spectacular way: they kick, wave their hands, swear, and all this with their eyes closed without waking up. As a result, both the sleeper and those who are sleeping next to him may suffer.
The end of REM sleep, like the end of the fourth stage, is usually marked by a short-term awakening. If you sleep without an alarm clock, sleep usually comes to an end simultaneously with the end of the last dream. Despite the fact that the time spent in bed helps to determine the optimal moment for awakening, daylight has the ability to wake us up instantly. When the light begins to penetrate the eyelids and hits the retina, the brain sends a signal to an area called the “suprachiasmatic nucleus.” At this moment, for many of us, the last dream is interrupted, we open our eyes and return to real life.
Or not? Perhaps most of all, the phase of fast sleep is striking in that it proves the ability of the brain to act independently of information from the senses. Like a musician, who locked himself in a secret studio, our mind is experimenting freely, selflessly fulfilling a task known to him alone.
When we are awake, the brain is very busy: you have to drive a car, go shopping, chat with each other, then chat. Earn money, raise children.