Night terrors are caused by intense brain activity during deep Stage 4 sleep.

In contrast, nightmares are a type of dream and occur during the REM sleep stage.

While nightmares have a frightening dream associated with them, night terrors do not.

Instead, they are characterized by a sudden awakening in a state of extreme fear or panic, often accompanied by sweating, screaming, and physical symptoms of terror.

A person who has had a night terror episode has no memory of a dream, and usually no idea of what launched him into such a state of extreme fear.

While a person who has had a nightmare can be comforted, it can be quite difficult to calm a person who has awakened from a night terror episode.

Many people who suffer night terrors don't completely wake up afterward, and some do not remember the event the next day.