Sleep is a necessary activity for the survival of our body. The exact causes of why we need to sleep are still unknown, but it seems that it mainly fulfills the function of letting our brain and body "rest" from daily activity. You cannot live long without sleep, more than three days without falling asleep at all can have disastrous consequences.
We don't all need to sleep the same number of hours. Generally, younger people, those who make intense physical or mental efforts, as well as certain personal characteristics, tend to need more sleep. A child may need to sleep about 10 hours a day, an adult between 6 and 8 hours, while an elderly person may have enough with 5 or 6.
It is very important that the sleep is of quality and without fragmentation. Five hours of deep and restful sleep can rest more than eight hours suffering from nightmares or discomfort. But sleep is not only a mere rest, but also serves to discharge a good number of tensions originated during wakefulness, and this is where our ability to dream plays its most important role..
Sleeping and dreaming are two closely linked processes, although they are not always accompanied. We do not dream during the entire time we are asleep, but only during certain specific periods called MOR (rapid eye movement) or REM (rapid eye movements) phases in English..
When we go to sleep, first of all there is a state of drowsiness or pre-sleep, which usually lasts for half an hour and during which we go from waking to sleeping with a progressive decrease in consciousness. Throughout this phase it is normal for visual or auditory illusions to occur (one has the illusion of hearing or seeing things that do not exist), as well as feeling cramps, dizziness or a stumbling sensation.
Later, when we are already immersed in a deep sleep, the phases of REM sleep follow one another with those of non-REM or superficial sleep. The first REM phase usually occurs between the first and second hours of sleep, appearing intermittently throughout the normal sleep period. This phase is also called the paradoxical sleep phase, since if we carry out an electroencephalographic tracing (EEG) we would see that it is very similar to when the person is awake, it is also the phase in which it is most difficult for the person to wake up.
It is in this phase that most of the dream activity occurs. Also in this phase a series of changes occur such as:
Much of these changes are due to the activation of the hypothalamus and pituitary, which increase the secretion of certain hormones such as testosterone, cortisol or growth hormone.
Today there is no uniform opinion about the meaning of dreams. In ancient times it was believed that dreams were in relation to the world of the superhuman, and that they brought divine revelations, especially about the future of the individual. Even Aristotle believed in the possibility of finding in dreams the indication of the onset of some disease of which we still cannot be aware during wakefulness due to lack of symptoms..
Sigmund Freud, in his famous work The Interpretation of Dreams, wrote that dreams were the fulfillment of our deepest desires, which we could not carry out while we were awake. According to him dreams would be the expression of an unsatisfied desire. Fundamentally attributed to them a character of a sexual nature. Later, Freud himself recognized that this was not always the case, and that they could also be the manifestation of a problem or concern, even the expression of fears of the unconscious, as occurs with nightmares or distressing dreams..
It can be said that to a greater or lesser degree the content of dreams is determined by the personality of the individual, his life and his past experiences. Thus, the most frequent content of dreams is constituted by the daily events experienced by the person, but distorted by the subconscious. In fact, it has been possible to verify that the content of dreams is related many times to the activity carried out during the same day and, very especially, to the images perceived during the moments immediately prior to falling asleep..
It can also be observed that many dreams host memories of childhood and youth, sometimes bringing us old memories that we thought were lost. This is a relatively normal phenomenon, perhaps it is due to the great importance that these memories usually have for the life of the person, although it has not been possible to demonstrate.
Some dreams have been observed that many people have, such as believing that we fall from a height, dreaming that we fly, that we lose a tooth or feel ashamed because we think that we are naked or badly dressed. The dream of falling from a height is almost always caused by the fact that, being already unconscious even of the sensation of contact and pressure on the bed, we move an arm or a leg in such a way that this movement becomes partly conscious but in a distorted way and we think we are falling. The dream of losing teeth is also attributed to a momentary oral sensation and that of feeling naked is related to the fact of having gotten out of the sheets that covered us.
In some people there are certain dreams that are repeated and that are generally fraught with anguish. Sometimes they can be the expression of psychological traumas that have not yet been assumed by the person.
Something curious in dreams is that generally we do not remember them, or only those that we have had in the last moment before waking up, and we even forget these with extraordinary speed, except perhaps those that have had a great impact on us. This is because in this way we do not end up storing meaningless memories in our brain that could confuse us, because when we wake up we have to know how to distinguish reality from reverie, so the latter is erased from our memory as a safety measure.
The dream ultimately manages to separate the individual from his waking life, as well as daytime pressures. But it has not yet been possible to establish exactly what its origins and definitive functions are, nor has it been scientifically proven that there are premonitory dreams, until now everything is more or less accurate hypothesis of our dream life.