The dream takes place mainly during the REM phase
Enigmas of the dream
Dreams, surrounded by a mystical and mysterious aura, have intrigued the human being since ancient times. More than 4,000 years ago, the inhabitants of ancient Babylon gave sacred importance to reveries. Not only did they have their own goddess, Mamu, who watched over people's good dreams, but also developed documents on the interpretation of dreams. In this regard, the story of the dream of the Babylonian king Nebuchadnezzar II, narrated in the Bible, that removed heaven and earth to try to know the meaning of his dream, calling a multitude of astrologers, fortune tellers and magicians, is celebrated. Sigmund Freud himself granted a great role to dreams, which he considered symbolic manifestations of repressed desires and a path to the unconscious. For him, the interpretation of these dream fantasies was one of the keys to understanding the psychology of his patients and applying a treatment.
Although adults spend between 20% and 25% of our time sleeping, science did not begin to dissipate the magic that surrounded them until relatively recently. It was from the mid-twentieth century, when tools such as the electroencephalogram were popularized, that we were able to peer, for the first time rigorously, into the ethereal and elusive world of dreams.
Today we know very peculiar details about the dream. For example, this process takes place mainly during the REM phase when we are asleep. This phase is characterized by rapid eye movements (abbreviations REM = Rapid Eye Movement) and high brain activity, similar to when we are awake. In contrast to this high activity, there is a low production of different neurotransmitters and our muscles are paralyzed. For that reason, we do not usually move when we are dreaming, although some neurodegenerative diseases such as Parkinson's cause muscular activity during sleep in affected people, which can lead to violent movements, accidents and involuntary aggressions towards bedmates.
We usually have 4 to 6 dreams every night, but we forget 95% of them within minutes of waking up. In other words, we all dream of sleeping, although the absolute majority of conscious memories of these dreams are lost in time like tears in the rain. On the other hand, a certain percentage of the population is able to be aware in their dreams and control them at will. They are called onironauts and experience the so-called lucid dreams.
Almost all of us see color images during dreams. However, some people only remember to contemplate these images as if it were an old television: in black and white. The blind also dream of images, as long as visual memories persist in their memory. If they became blind from birth or before 5-7 years of age they are unable to have dreams with visual experiences.
We have learned a lot about sleep in recent decades thanks to the innovative tools that study brain activity. We know, for example, that the rational brain, the prefrontal cortex, is usually deactivated, leading to the typical creative chaos and lack of rational and logical limits of dreams. We also know that dreams originate in our memories and experiences accumulated and recorded through the senses. Even so, we still have no idea of the main question: why do we dream?
There are many hypotheses in this regard that try to explain this nocturnal habit. A possible explanation suggests that sleep is a mechanism to reinforce the memories of the day and thus favor its permanence in long-term memories. Different experiments in both laboratory animals and humans point to this possibility. For example, the hippocampus, an area of the brain involved in memory, is especially active when we are in the arms of Morpheus.
When mice are not allowed to have REM dreams (but they do sleep) they have considerable problems remembering details in different tests compared to their partners who had complete sleep cycles. It has also been observed that people who remember in dreams abilities such as driving, playing an instrument or leaving a maze enhance their learning in these tasks. Therefore, when some activity does not come out because we do not have enough practice, going to bed and dreaming about it can make it a little easier the next day.
At the same time that the dream helps us to settle memories, it would also help us to forget by refreshing our memory by eliminating superfluous or unimportant memories that occurred before. The dream would serve, as well, as an organizer of memory that highlights the important and loose ballast with the irrelevant.
Other hypotheses indicate that the dream would help us learn to face situations that cause stress, discomfort or a challenge in a safe environment with greater creativity. That would explain such striking facts as why the blind have four times more nightmares than the general population and that, in addition, these nightmares consist, with high frequency, of accidents when traveling blindly down the street. On the other hand, the role of the dream to process past traumas or as an element to fulfill our wishes has also been pointed out.
Despite the variety and number of hypotheses raised, not all scientists are in favor of the dream having an essential function. Other researchers raise the possibility that sleep is something accidental, a chaotic and meaningless noise that appears in our brain through neuronal reconnection processes during the time we are asleep.
In short, everything indicates that the mystery behind the existence of dreams will continue with us for much longer. Let's enjoy them despite our ignorance. Because, as the famous Antonio Machado said: "If it is good to live, it is still better to dream, and best of all, to wake up."