A night terror, also known as pavor nocturnus, is a parasomnia sleep isorder 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.