Nightmares: Terrors of the Night.Sigmund Freud, who was a famous researcher of the theory of dreams, thought childhood punishments caused nightmares. Also, according to modern sleep laboratory's experiment rapid eye movement occurs during nightmare. Nightmares and night terrors have two major differences. Night terror happens in early night with suddenly awaking, sweating, body moving, and sometimes crying or screaming. Moreover, especially for children, body moving leads a sleepwalking. According to some people, these episodes feel like mysterious things, as if evil causes these things. On the other hand, Nightmares happen about 3 hours before people awake, moreover they happen during the time called REM. At this time, the pulse is not so fast as the night terror situation because, REM-sleep affect to the human body to numbness. In addition, people who have experienced night terror could not remember what they experienced. However, people who have experienced nightmares remember what happened. Right now, nobody believes demons or evils produce nightmares. Actually, the physical illness, mental illness, stresses and helplessness produce nightmares. From the research of the people who have experienced nightmares, it has been learned that most people continue to have nightmares from childhood to the present.