Hi,

Night terrors, also known as sleep terror or pavor nocturnus, is a parasomnia sleep disorder characterized by extreme terror and a temporary inability to regain full consciousness. Night terrors happen during deep sleep .

The person wakes abruptly from the fourth stage of sleep, with waking usually accompanied by gasping, moaning, or screaming. It is often impossible to fully awaken the person, and after the episode the person normally settles back to sleep without waking.

Children from age four to six are most prone to night terrors, and they affect about three percent of all youngsters. A child having a night terror will often wake up screaming. He or she may be sweating and breathing fast.

At this point, your child may still be asleep, with open eyes. He or she will be confused and might not answer when you ask what's wrong. Your child may be difficult to wake. Episodes may recur for a couple of weeks then suddenly disappear.

For more information about night terrors and other sleep disorders can be found at :
http://www.sleepdisordersguide.com