REM phase: the most important stage of sleep

The REM phase begins ninety minutes after falling asleep: breathing accelerates, the classic eye movements appear and the most vivid nightmares also arise. Curiously, it is during this stage that the brain shows the same activity as if it were awake. The reason? You are about to carry out one of your most important tasks.

It has been more than 50 years since this stage of sleep was discovered. Now, it should be said that the rapid eye movement (REM) sleep phase or REM phase in English (for r apid eye movement) continues to harbor many enigmas. We also know that he acts like a true sculptor, discarding what he considers irrelevant or of little use to keep all those data that he assumes are significant.

However, Experts do not know what mechanisms guide the brain to suddenly enter this amazing REM phase.. Thus, studies such as the one published in the journal Nature and carried out by neurologists Jon Lu and David Sherman, they tell us about a kind of “switch” located in the brain stem.

It would be, rather, a set of specialized neurons that allow us to cross, so to speak, that threshold. They allow us to move into that world where dreams are more vivid, where some people can sleepwalk and where our brain reorganizes all those memories that it has been encoding during the day.

The REM phase and the fundamentals of sleep

When Sherlock Holmes told Dr. Watson that the best remedy for all problems was sleep, he was not wrong.. When our body rests we regain energy and health. A restful night’s sleep is an ideal mechanism to reduce stress, to see reality from other perspectives and to think more clearly and accurately.

Sleep is a biological need. Letting our brain transit and delve into the REM phase is essential for most living beings. What’s more, we know that all of us usually have between 4 and 9 sleep cycles, each divided into 5 phases.. The latter are REM territory, where this paradoxical sleep provides us with a restful rest and allows our brain to carry out essential tasks.

It is also known that Newborns as well as younger children spend most of their sleep cycle in the REM stage., in this way they better integrate each experience in what is undoubtedly the most important stage of their development. However, from the age of 6 this stage is noticeably reduced and lasts the same duration as in an adult.

On the other hand, as scientists explain to us One of Karni and BS Rubenstein In a study published in the journal ScienceREM sleep is key to our perception and attentionto respond to stimuli, to learn from our environment and survive in it.

Likewise, we also know that All mammals, as well as birds, dream, and they have their REM phase. However, there is still a lot of study ahead in non-humans, since initially it was believed that marine animals do not dream. Cuttlefish and octopuses have proven the opposite.

What happens during REM sleep in our brain and body?

REM sleep is also called “paradoxical.” due to the peculiarity of the brain waves that appear in this stage of rest: they are desynchronized, very fast and low voltage. In addition, brain activity in general is very similar to that of wakefulness.

On the other hand, the brain area that according to experts regulates this phase of sleep is the brain stem. The cortical and thalamic neurons are more depolarized at this stage, and a type of neurotransmitter also appears in greater abundance: acetylcholine.. Likewise, when we reach the REM phase we usually experience the following:

Accelerated breathing. Eye movement. Muscle relaxation. Sexual arousal. Appearance of vivid dreams.

To better understand how the REM phase acts and appears, let’s now see what the phases of sleep are. You can see them in detail in the following sections.

Stage 1

In this first stage, awakenings are common, as well as that feeling of sudden falls.. Muscle tone relaxes little by little and alpha and theta brain waves predominate.

Stage 2

The sleep becomes deeper, the heart rate decreases, as well as body temperature. At this point, the body prepares to enter the most important phases of rest.

Stages 3 and 4

In these phases sleep is deep. Delta waves predominate and sleep disorders, such as night terrors and sleepwalking, may already appear. During this stage of NON-REM sleep the body repairs itself, tissues regenerate, Cells that are no longer useful are eliminated and the immune system is purified. In the case of children, the growth of bones, muscles, etc. is stimulated.

REM stage

Between 90 and 100 minutes of sleep have already passed and we finally reach the REM phase. Brain waves present the same activity as if we were awake, our dreams present a narrative with greater meaning and the body loses muscle tone. Theta waves predominate and the brain then begins to integrate the lived experiences into long-term memory.

This cycle described will be repeated throughout the night between 4 and 5 times. And in each cycle, the REM stage will last longer, starting with 10 minutes until reaching an hour (two if we are under 30 years old and half an hour if we are over 65 years old).

Evolution of sleep throughout life

Sleep cycles, as has been said, vary throughout life. It is no coincidence that children need 10 hours of sleep and older adults have trouble sleeping. Let’s see the evolution of this biorhythm throughout life:

Newborns spend 50% of the day sleeping. Starting from the fourth month of life, this is reduced to 40% and this percentage will decrease over the years. In biological adulthood, this percentage is 20%. When approaching In old age, individuals begin to have fragmented sleep, that is, they wake up often at night. The REM phase, although it is reduced in duration, takes less time to appear when the subject falls asleep.

REM sleep behavior disorder (RSBD)

This is a condition that occurs during the REM sleep stage. It is characterized by vigorous motor behaviors, nightmares and the absence of muscle atony. Likewise, it usually occurs in people over 55 years of age.

The TCSR It is classified as a parasomnia (alteration of behavior during sleep). However, recent research suggests that it is not a simple sleep disturbance, but rather tends to be the first manifestation of a neurodegenerative disease, such as Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy.

The dreams of patients with TCSR often have unpleasant content which includes arguments, fights, chases, robberies, animal attacks and falls off cliffs. In the dream, the subject is usually the one attacked, he may or may not recognize the faces of his attackers and the context is usually located in situations or places from the subject’s past.

Finally, Those affected can scream, moan, sob, cry, talk (in most cases the content is not understood), say or shout swear words or vulgar expressions and sometimes they can even laugh or sing.. The movements are usually slaps, punches, kicks, and less frequently they can bite, sit up in bed, jump and fall out of bed, get up and walk around the room.

To take into account

As we can see, The relevance of maintaining good sleep hygiene is key to recovering energy. Sleeping well, and thus reaching the REM phase, is key to taking care of our cognitive processes, memory, attention, perception, the ability to react more effectively to daily stimuli, etc.

Shakespeare once said that the man who does not feed on his dreams grows old soon. We could also add that The person who does not sleep does not dream either, and those who live deprived of dreams do not live as they deserve.

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