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

In this stage of brain activation, the nervous system does not seem to sleep.

By now, the vast majority of the population is familiar with or has heard at some time of the concept of REM phase or REM sleep. We know that it is part of our sleep and that it is at least somewhat different from the rest of our sleep, the non-REM sleep.

Many people do not know what makes this sleep such a necessary element 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 sleep

Sleep is an essential need for human beings and for most living things. and for most living beings. Our organism is a structure that continuously consumes energy, requiring the elements of our "machinery" to rest in order to function properly.

Sleep is essential. However, sleep is not something uniform that appears abruptly. In fact, during sleep there are several cycles composed of different phases, in which different functions are altered and in which our brain reduces or increases certain types of energy. our brain reduces or increases certain types of bioelectrical activity.. Specifically, we usually have between 4 and 9 of these cycles, each of them divided into five phases. These phases usually follow a certain order.

First of all, in phase 1 we find ourselves in a phase of numbness, in which our consciousness is gradually reduced even though at the slightest stimulation we are able to wake up. Our brain registers mainly alpha waves, which are the usual ones in states of relaxation even when we are awake.

Subsequently and if nothing interrupts it, we enter a second phase, in which eye movements are completely reduced and there is a marked decrease in muscle tone. We become increasingly relaxed and disconnected from our surroundings. If we observe with an electroencephalogram the functioning of the brain at the level of waves we observe how theta waves prevail, with the peculiarity that oscillations appear in the cerebral activity in the form of K complexes and spindles. in the form of K-complexes and sleep spindles..

After these phases, both of light sleep, we would enter phases 3 and 4 of sleep, known as deep sleep. These are the phases in which true rest of the organism takes place. Physical activity is practically non-existent for most people, although there is an increase in muscle tone. there is an increase in muscle tone. Night terrors and other parasomnias such as sleepwalking occur during these sleep phases. 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 REM sleep phase.

The REM or REM sleep phase

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

It is considered to be desynchronized sleep. The brain activity is similar to what we would have while awake. or in the phases of numbness, there are abundant theta waves with sawtooth (the latter especially characteristic of the parietal areas of the brain) and beta. The body remains totally immobile and paralyzed, with complete disappearance of the muscular tone except in eyes and diaphragm.

It is in the REM phase of sleep that dreams and nightmares appear, as well as the capacity to remember them. There is also an increase in physiological activation (despite muscular atony), increasing Blood pressure, heart rate and respiratory rate, and erections are common. As the cycles go on, the amount of REM sleep increases.

Main function of this stage of sleep

The functions of this type of sleep are not clearly defined. However, it is considered that during REM sleep we reorganize our mental contents, by fixing the new memories and integrating them into the memory, while discarding those while discarding information or memories considered irrelevant. Thus, this type of sleep converts the experience into a memory stored in long-term memory.

Likewise, it is during these phases that the highest level of brain development occurs, being fundamental for its maturation, especially during the growth stage. It is considered desynchronized sleep.

This is not only important at a cognitive levelIt is also important in terms of sensory processing, as studies such as those of Marcos Frank at the National Institute of Health in the United States seem to indicate, for example, by allowing the ERK protein (a protein that is only activated during this phase of sleep) to fix the changes in the visual cortex and adjust the connections that allow the development of visual perception. The same is true for other abilities.

Evolution throughout the life cycle

Throughout life our biorhythms and sleep cycles vary greatly our sleep cycles vary enormously. We do not sleep the same in our first year of life as we do in our thirties, and even less than we do in our eighties.

Newborns, for example, spend a large part of the day sleeping, with about 50% of this time in REM sleep. From the fourth month this percentage is reduced to 40& and begins to be preceded by non-REM sleep. As the child grows older, the amount of time spent awake increases and the amount of sleep decreases. At the age of approximately six years, sleep patterns and cycles stabilize, resembling adult sleep.

During adulthood the approximate proportion of REM sleep is 20%, with the remainder being non-REM sleep. With age, total sleep time decreases and becomes fragmented, especially when we reach old age, with a large number of nighttime awakenings. The amount of sleep is dramatically reduced, including REM sleep. Despite this, a shorter latency of REM sleep is observed (it takes less time to appear).

Bibliographical references:

• McCarley, R.W. (2007). Neurobiology of REM and NREM sleep. Sleep Med, 8.