Physiology of Dreaming

Abstract

Dreaming has been a subject of cogitation since remote Antiquity. In ancient Greece, Socrates, Plato and Aristotle discussed about the meaning of dreams, concluding that the prevailing mistic and mythic concepts about them were incorrect. Instead, they thought that dreams were not provoked by spirits, ghosts or gods, which took over the mind to express themselves through dreaming. Aristotle[ 1 ], who had carefully observed several animal species while asleep, noticed that movements of several of their body parts were quite similar to those performed by humans during dreaming. Some of his statements, hereby reproduced in a simplified form from his book on sleep and dreams, briefly illustrate his contribution to the study of this subject: "All creatures that have four limbs and are sanguine (mammals) display signs that they dream while asleep. It seems that not only humans but also dogs, cows, sheep and goats and the entire family of four-legged viviparous animals do dream." "As to the oviparous creatures, it is obvious that they sleep but it is impossible to state that they dream. The same holds true for animals that live in water, such as fishes, molusks, crustacea and other similar animals; it is impossible to invoke as a proof that they do sleep the shutting of their eyes, inasmuch as they do not have eyelids but it is obvious that they periodically do rest, immobile, what perhaps does explain why at night their predators attack them heavily and devour them. When they sleep, fishes keep quiet, with no apparent movements, and then they can be easily fished with a hand." "Insects are also creatures that do sleep, so much so that they can be seen resting with no movements whatsoever. This is specially true as to bees, that at night do interrupt their hum, "even if they are exposed to the light of a lantern". "Dreams are not ghosts (phantasmata), since they are closely related to the events of the previous day". In Greece dreams were called oneiros , a word that originated the adjective oniric but that meant not exactly what was dreamed about neither the dreaming process, which was not rated as something important, but the phantasmata , i.e. the apparitions. As a prevailing concept even today, dreams were considered premonitory, messages from the dead and mystical warnings. Herodotus, in his Histories , the first textbook on History ever written, tells that the Persian King Xerxes dreamed quite often about the war he was about to fight against Athens. He properly related such dreams to his concern with that important war. His personal oracle, however, disagreed and convinced him that his dreams were warnings from the gods. Xerxes, in fact, had discovered an important aspect of dreams but his oracle discarded such an explanation, in favor of the mystic one. In the past, most civilizations boasted having wise people who could tell the meaning of dreams if conveniently paid for that, a fancy profession that still has its counterparts in modern nations. Psychoanalysis considers dreams as an important window to the unconscious world, what makes dream interpretation a crucial factor in psychonalytic diagnosis and treatment. However, psychoanalysts take into account only a few dreams that are occasionally recalled, despite the fact that we dream four or five episodes every night, what means that the fraction of dreams we can is a of what we in fact do as Psychoanalysis also considers dreams as the of this is true as to only a few dreams, several that most dreams are closely related to the events of the previous as Aristotle had Socrates, Aristotle and were to the prevailing of the that mystic and to the of dreams as their However, they that the dreams were by the and who discovered that the mind is in the not in the that dreams were originated in the the the first of in his book for the of the of sleep and despite his of dreams, by of the of that the dreams with a those with an and those in which the or even in fact, that only could be as an oniric the of the a who in and was a and that and at night, which he to the in by then the of of the entire and in the and in the that had been by and that important into and this of the also about the in as considered dreams or to but could not to their The ancient to dreaming but also considered them the several and to the and meaning of in his book of , in with movements as a of dreams, and in and its , also took the movements of and during sleep as a of important of in his book in and , in and several in the ], that at and do a concept that still despite which most that on sleep still that dreaming is the of the several on oniric of the who the that the ancient of the several at night his during sleep and that their movements while were related to their dreams, as Aristotle had The in an important, the of , the of people they parts of the body during sleep and them to their discovered that most dreams during the of the night and that of them are closely related to the events the important were by the of which was was in the of several of dreams as related to their do not from modern of the same in in his book and of a no and with dreams, which 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