Sleep Terror (night terror)

A night terror, also known as pavor nocturnus, is a parasomnia sleep disorder characterized by extreme terror and a temporary inability to regain full consciousness. The subject wakes abruptly from slow-wave sleep, with waking usually accompanied by gasping, moaning, or screaming. It is often impossible to fully awaken the person, and after the episode the subject normally settles back to sleep without waking. A night terror can rarely be recalled by the subject. They typically occur during non-rapid eye movement sleep.

Night terrors versus nightmares

Night terrors are distinct from nightmares in several key ways. First, the subject is not fully awake when roused, and even when efforts are made to awaken the sleeper, he/she may continue to experience the night terror for ten to twenty minutes. Unlike nightmares, which occur during REM sleep, night terrors occur during slow-wave sleep, the deepest level of NREM sleep. Even if awakened, the subject often cannot remember the episode except for a sense of panic, while nightmares usually can be easily recalled.

Unlike nightmares, which are frequently dreams of a frightening nature, night terrors are not dreams. Usually there is no situation or event (scary or otherwise) that is dreamt, but rather the emotion of fear itself is felt. Often, this is coupled with tension and apprehension without any distinct sounds or visual imagery, although sometimes a vague object of fear is identified by the sufferer. These emotions, generally without a focusing event or scenario, increase emotions in a cumulative effect. The lack of a dream itself leaves those awakened from a night terror in a state of disorientation much more severe than that caused by a normal nightmare. This can include a short period of amnesia during which the subjects may be unable to recall their names, locations, ages, or any other identifying features of themselves.