Dream: Definition, Stages, Effects and Purposes

The dream is a physiological behavior that is common in all human and animal species, where not clearly known the exact functions, but appears to be essential for survival, and that deprivation prolonged of it leads to serious physical deterioration followed by cognitive loss and, finally, death.

Sleep disturbances are clinically important, as they are indicators of almost all types of psychiatric ailments.

What is the dream?

It is a natural, repeating state of mind and body characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with the environment. It is distinguished from wakefulness by a reduced ability to react to stimuli, but it is more easily reversed than being in a coma.

It occurs in periods of repetition, in which the body alternates between two different modes: REM and non-REM sleep. Although REM stands for “rapid eye movement,” this mode of sleep has many other aspects, including virtual paralysis of the body.

During sleep, most of the body’s systems are in an anabolic state, which helps to restore the immune, nervous, skeletal and muscular systems; These are vital processes that maintain mood, memory, and cognitive function, and play an important role in the function of the endocrine and immune systems. The internal circadian clock promotes sleep every day at night, the various purposes and mechanisms of sleep are the subject of substantial ongoing research.

Humans can suffer from various disorders of sleep , as dyssomnias as insomnia , hypersomnia, narcolepsy and apnea sleep , parasomnias such as sleepwalking and REM behavior disorder, bruxism and disorders of sleep circadian rhythm. The advent of artificial light has substantially altered sleep time in industrialized countries.

Stages of sleep

There are five stages, scientists classified them according to the characteristics of the brain and body. Stages 1,2,3 and 4 are classified as “non-REM sleep” and the fifth stage is REM sleep. In general, the brain wave frequencies and amplitudes of an EEG are used to differentiate the different stages, along with other biological rhythms, including eye movements and muscle movements.

Non-REM sleep

Stage 1

It is the lightest stage, the brain frequency is slightly slower than during waking time, we go in and out of sleep and we can wake it up easily, our eyes move very slowly, and muscle activity slows down. People who wake up from stage 1 sleep often recall fragmented visual images. Many also experience sudden muscle contractions called hypnotic myoclonus, preceded by a sensation of beginning to sag.

These sudden movements are similar to the “jump” we do when we are startled, there is muscle tone present in the skeletal muscles, and breathing occurs at a regular rate.

Stage 2

Sleep deepens during this stage and our muscles relax even more, physical sensations are significantly attenuated and our eyes do not move, electrical activity in the brain occurs at a lower frequency than when we are awake. About half of our total sleep time is spent in stage 2. Stages 1 and 2 are known as the light sleep phase and together they last around 20-30 minutes. We go back to stage 2 several times during the night. The body begins to prepare for deep sleep, as the body temperature begins to drop and the heart rate slows down.

Stage 3 and 4

In stage 3, extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves. In stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone up during stages 3 and 4, which together are called deep sleep. There is no eye movement or muscle activity. People who wake up during deep sleep do not adjust immediately and feel dizzy and disoriented for several minutes after waking up. Some children experience nocturnal enuresis, night terrors, or sleepwalking.

They are progressively deeper stages and are also called “delta or slow wave sleep.” During it, the EEG shows a much slower frequency with high-amplitude signals (delta waves), a sleeper is often difficult to wake up. As humans age they spend less time in deep slow wave sleep and more time in stage 2 sleep.

Slow wave is generally known as deep sleep, and it is made up of the deepest stage of NREM. In stage three, we see the highest activation thresholds, such as difficulty awakening, and so on, after being awakened, the person will generally feel quite dizzy, and cognitive tests that have been administered after being awakened from the third stage show that for about half an hour or so, and compared to awakenings of the other stages, mental performance is moderately impaired, this is a phenomenon known as sleep inertia. When deprivation occurs, there is usually a strong slow-wave rebound, which is a highly active state, and not brain dormancy as previously believed. In fact,

REM sleep

Between 80 and 100 minutes after falling asleep, the deep sleep phase comes to an abrupt end, which is accompanied by a change in sleeping position. Our sleep changes to stage 2 for a few minutes before the EEG graph makes an abrupt change in the space of a few seconds, this shows that REM sleep is beginning; our heart rate increases and breathing becomes faster.

Electrical activity in the brain creates small and rapid movements, similar to those seen when falling asleep, our muscles are completely relaxed, but our eyes make rapid movements while remaining closed, this is where the phrase rapid eye movement (REM) comes from. ).

Men occasionally experience erections during this phase, and women may have increased blood flow to the genitals, the production of digestive juices increases. It is during REM that we have most of our dreams, as it accounts for about 20 percent of the night, the percentage is considerably higher for infants and toddlers.

When healthy people are in a REM sleep state, the muscles of our body are deeply relaxed, if not for this we could act out our dreams, with potentially disastrous consequences, this is the most likely reason why the brain places the body in this deep state of relaxation that borders on paralysis (known as atony). However, when a person suffers from some conditions, such as Parkinson’s disease , REM atony does not occur.

Purposes of sleep

Scientists have not yet identified a reason why we need to sleep every night. However, based on research and monitoring of sleeping human brains, they have some ideas. Among its many functions:

It offers the body the opportunity to recover from the wear and tear of everyday life. Many researchers have suggested the restorative effects of sleep, this not only means that the body rests, but that cells are actively regenerating and body temperature, heart rate and respiration are decreased to conserve energy.

Facilitates learning and memory . Not only do you need to rest to maintain the attention and concentration needed to learn new tasks, but according to the Harvard Division of Sleep Medicine, sleep is a time for the brain to consolidate memories, making learning easier.of new things. People who sleep after learning how to play a video game generally perform much better at the game later than those who stay awake. Even more intriguing, a recent study in Natural Neuroscience showed that people can even learn entirely new behaviors (in this case, associating unpleasant and pleasant smells with certain sounds) while fully asleep.

It plays a role in immune function. Your body makes special proteins called cytokines, which help your immune system fight infection. According to the US Department of Health and Human Services, more of these proteins are made during sleep when you’re sick, which is one of the reasons you can feel so tired when you have the flu. Rest gives your body the time it needs to produce these infection-fighting proteins and to restore well-being.

Physiological changes during sleep

Many physiological variables are controlled during wakefulness at levels that are optimal for body function, our temperature, blood pressure, and levels of oxygen, carbon dioxide, and blood glucose remain fairly constant during wakefulness. During sleep, however, physiological demands are lowered and temperature and blood pressure drop, in general, many of our physiological functions, such as brain wave activity, respiration, and heart rate, are quite variable when we are awake or during REM, but they are extremely regular when we are in non-REM sleep.

Brain activity

For centuries, doctors believed that sleep was a period of brain inactivity, yet research over the past 60 years has shown us that the brain remains active during sleep. There is a progressive decrease in the rate of activation or “firing” of most neurons throughout the brain as sleep progresses from wakefulness to non-REM. Furthermore, neuron firing patterns change from an apparently random and variable pattern of activity during wakefulness to a much more coordinated and synchronous pattern during non-REM.

Body temperature

Through a process known as thermoregulation, our body temperature is controlled by mechanisms such as shaking, sweating, and changing blood flow to the skin, so that body temperature minimally fluctuates around a set level during wakefulness. Right before we fall asleep, our bodies begin to lose some heat to the environment, which some researchers believe actually helps induce sleep.

During sleep, the temperature of our core system is lowered by 1 to 2 ° F. As a result, we use less energy by maintaining our body temperature. It has been hypothesized that one of the main functions is to conserve energy in this way. Body temperature is still maintained, albeit at a slightly reduced level during non-REM sleep, but during REM sleep the body temperature drops to its lowest point. Snuggling into bed under a blanket during the usual 10 to 30 minute REM sleep periods ensures that we don’t lose excessive heat to the environment during this potentially dangerous time without thermoregulation.

Respiratory changes

Our breathing patterns also change during sleep, when we are awake, breathing is usually quite irregular, as it is affected by speech, emotions , exercise, posture and other factors. As we progress from wakefulness to non-REM stages, our respiratory rate decreases slightly and becomes very regular. During REM sleep, the pattern becomes much more variable again, with a general increase in respiratory rate.

Cardiovascular activity

One of the possible functions is to give the heart a chance to rest from the constant demands of waking life. Compared to wakefulness, during non-REM there is an overall reduction in heart rate and blood pressure. During REM sleep, however, there is a more pronounced variation in cardiovascular activity, with general increases in blood pressure and heart rate, in addition, changes in blood flow that cause erections in men or clitoral swelling in men. women are characteristic.

Increased physiological activity

For the most part, many physiological activities are reduced during sleep. For example, kidney function decreases and urine production decreases, however some physiological processes can be maintained or even increased, one of the major changes induced is an increase in the release of growth hormone, certain physiological activities associated with digestion , cell repair and growth are greatest during sleep, suggesting that cell repair and growth may be an important function.

Effects of sleep deprivation

If you’ve ever spent a night tossing and turning, you already know how you’ll feel the next day: tired and cranky, but missing the recommended 7-9 hours of nighttime sleep does more than make you feel groggy and grumpy. The long-term effects of sleep deprivation are real, it lowers your mental abilities and puts your physical health at real risk. Science has linked poor sleep to all manner of health problems, from weight gain to a weakened immune system.

Your body needs sleep, just like it needs air and food to function at its best, during sleep your body heals and restores its chemical balance, your brain forges new connections and helps memory retention. Without enough sleep, your brain and body systems will not function normally, it can also dramatically decrease your quality of life. A review of 16 studies found that getting less than 6 to 8 hours of sleep per night increases the risk of premature death by about 12 percent.

The obvious signs of lack of sleep are:

  • excessive drowsiness
  • yawn.
  • Irritability.
  • Daytime fatigue

Stimulants like caffeine aren’t enough to override your body’s deep need for sleep – behind the scenes, chronic sleep deprivation can interfere with your body’s internal systems and cause more than just the initial signs and symptoms listed above. Many studies make it clear that deprivation is dangerous, since people who are tested using a driving simulator perform as poorly or worse than those who are intoxicated, it also increases the effects of alcohol on the body, making a person fatigued who drinks will be much more affected than someone who is well rested.

Georgia Tarrant
 | Website

Hello, how are you? My name is Georgia Tarrant, and I am a clinical psychologist. In everyday life, professional obligations seem to predominate over our personal life. It's as if work takes up more and more of the time we'd love to devote to our love life, our family, or even a moment of leisure.