Definition

By Mayo Clinic staff

Nightmares are disturbing dreams associated with anxiety, fear or terror. Nightmares are common. They begin in childhood and tend to decrease after about age 10. However, some people have them as teens or adults, or throughout their lives.

Until age 13, boys and girls have nightmares in equal numbers. At age 13, nightmares become more prevalent in girls than boys.

Nightmares seem real, often becoming more disturbing as the dream unfolds. But nightmares usually are nothing to worry about. They may become a problem if you have them frequently and they cause you to fear going to sleep or keep you from sleeping well.