REM phase: what is it and why is it fascinating?

Today, a large majority of the population knows or has heard on some occasions about the concept of REM phase or your REM. We know this is part of our dream and, at the very least, it has some differences from the rest of sleep, non-REM.

A lot of people don’t know what makes this dream so necessary for us. That is why, in this article, we will make a brief commentary on what REM sleep is and its peculiarities.

    The phases of sound

    Sleep is an essential necessity for human beings and for most living things. Our body is a structure that continually consumes energy, requiring the elements of our “machinery” at rest to function.

    Sleep is the key. However, sleep is not a uniform thing that suddenly appears. In fact, during sleep there are several cycles composed of different phases, in which different functions are changed and in which our brains reduce or increase certain types of bioelectric activity. Specifically, we usually have between 4 and 9 of these cycles, each divided into five phases. These phases generally follow a certain order.

    First of all, in phase 1 we find a phase of numbness, in which our consciousness is gradually reduced, although at the slightest stimulation we can fade away. Our brain primarily registers alpha-type waves, which are the usual states of relaxation even when we are awake.

    Later, and if nothing stops, we enter a second phase, in which eye movements are completely reduced and there is a marked decrease in muscle tone. We are more and more relaxed and disconnected from the environment. If we observe with an electroencephalogram the functioning of the brain at the wave level, we observe how theta waves prevail, with the particularity that oscillations appear in brain activity. in the form of K complexes and sleep spindles.

    After these phases, both of light sleep, we entered phases 3 and 4 of sleep, called deep sleep. These are the phases in which there is real rest for the body. Physical activity is virtually non-existent for most people, although there is an increase in muscle tone. Night terrors and other parasomnias such as sleepwalking occur during these phases of sleep. Brain wave recording would show a general prevalence of delta waves.

    These phases correspond entirely to non-REM sleep. But after them we can still find one more phase, the REM or MOR phase.

      The REM or MOR phase

      The REM phase (REM being the acronym for Rapid Eye Movement) or MOR (rapid eye movements), is one of the most important phases of sleep. It is characterized by the presence of high brain activity, which may be visible when performing rapid and constant eye movements.

      It is considered asynchronous sleep. Brain activity is similar to what we would have awakened or in the phases of numbness, and there are abundant theta waves with sawtooth (the latter particularly characteristic of the parietal areas of the brain) and beta. The body remains completely still and paralyzed, with complete disappearance of muscle tone except in the eyes and diaphragm.

      It is in the REM phase of sleep that dreams and nightmares appear, as well as the ability to remember them. There is also an increase in physiological activation (despite muscle atony), an increase in blood pressure, heart rate and respiratory rate, and the appearance of erections is common. Over the course of the cycles, the amount of REM sleep increases.

      Main function of this stage of sleep

      The functions of this type of sleep are not clearly delineated. However, it is considered that during REM sleep, we reorganize our mental content, fix new memories and integrate them into memory at the same time, we reject such information or memories considered irrelevant. Thus, this type of sleep transforms the experience into memory stored in long-term memory.

      It is also during these phases that the highest level of brain development occurs, which is essential for its maturation, especially during the growth phase. It is considered asynchronous sleep.

      this it is not only cognitively importantBut also in terms of sensory processing, as studies such as those by Marc Frank at the National Institutes of Health in the United States seem to indicate, by allowing for example the ERK protein (a protein which is only activated in this phase of sleep) to finish fixing the changes in the visual cortex and adjusting the connections that allow the development of visual perception. The same goes for other skills.

      Evolution throughout the life cycle

      Throughout life, our biorhythms and our sleep cycles vary enormously. We don’t sleep the same way during our first year of life than at age 30, let alone at age 80.

      Newborns, for example, spend most of their day sleeping, with about 50% of that time in the REM phase. From the fourth month, this percentage is reduced to 40% and begins to be preceded by non-REM sleep. As the child grows, the time they stay awake increases and the amount of sleep decreases. By about the age of six, sleep patterns and cycles stabilize, resembling adult sleep.

      In adulthood, the approximate proportion of REM sleep is 20% and the rest is non-REM sleep. With age, the total duration of sleep is reduced and fragmented, especially when we reach old age, with a lot of nocturnal awakenings. The amount of sleep is significantly reduced, including that of the REM type. Despite this, a lower latency of REM sleep is observed (it takes less time to appear).

      Bibliographical references:

      • McCarley, RW (2007). REM and NREM sleep neurobiology. Sleep Med, 8.

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