Nightmare (French cauchemar, from other French caucher “to crush” and mare “night ghost”) is an alarming, frightening, terrible dream.
Night terrors are considered a non-organic sleep disorder and occur during REM sleep, which lasts between a few minutes and half an hour. The nightmare usually ends with a frightened awakening, usually immediately followed by the realization of awakening from sleep, associated with the return of a sense of space and time.
In mythology, a nightmare is often explained by the action of otherworldly forces. In Russian folklore, the nightmare is considered the pranks of the brownie. In Germanic mythology, elves were considered guilty of nightmares, as they were responsible for dreams. Elves were depicted sitting on the chest of a sleeping person, creating an unpleasant feeling of pressure (see picture). Night terrors are often the subject of literature and horror films.
Usually a dream in the form of a nightmare takes on explicit plot forms, with the dreamer himself at the center of the plot. The plot develops in the form of persecution, a series of any accidents, the result of which, as a rule, is the dreamer's death, with awakening at the last moment.
In psychoanalysis, according to Freud, a nightmare is explained as a state of sleep based on the strong suppression of repressed (most often sexual) desires.
Awakening from a night's sleep or slumber with a detailed and vivid reproduction of a dream of intensely frightening content, usually involving a threat to life; awakening can occur at any time of sleep, although, as a rule, in the second half of it.
Upon awakening from a nightmare, a normal level of wakefulness and orientation is quickly achieved.
Dreams and the sleep disturbances that result from them lead to marked distress. Night terrors are characterized by instantaneous awakening from a deep sleep phase, heralded by jerky body movements and frequent screams. The heart rate increases, sweating, the person shakes, in some cases even nauseated. Then he abruptly gets up from the bed with his eyes wide open, but he does not see anything and no one around him (the pupils are dilated and do not respond to the light stimulus). It can be difficult to talk to him at this moment, because despite the full functionality of the brain, the person is in a state of shock, and can get injured or inflict it on others. Episodes can last from one to several minutes, during which the person may even get up and take a few steps. After a while, he falls asleep again and, as a rule, does not remember anything the next morning.
Night terrors occur in people suffering from parasomnia within one to four hours of falling asleep, during a time when deep sleep is dominant and dreams are almost non-existent.