A night terror isn't a nightmare as such, it is a sleep distraction, like a nightmare, but with a far more dramatic presentation. It usually occurs 2-3 hours after the person has fallen alseep, nightmares usually happen later on in the night closer to the morning and you usually wake up frightened and scared, but with a night terror, you wake up not remembering what happened at all, you just react to it in a rapid way.
Night terrors are caused by over-arousal of the central nervous system (CNS) during sleep. The CNS regulates sleep and waking brain activity, and is still maturing in children. Night terrors are usually inherited - about 80% who have night terrors have a family member who also experienced them or sleepwalking (a similar type of sleep disturbance).
There's no treatment for night terrors, but you can help prevent them. Try to:
Reduce your stress; Establish and stick to a bedtime routine that's simple; Make sure you get enough rest; Prevent yourself from becoming overtired by staying up too late;
It's best not to try to wake kids during a night terror. Attempts usually don't work, and kids who do wake are likely to be disoriented and confused, and may take longer to settle down and go back to sleep.