Nightmares are bad, unpleasant dreams.
Children wake up frightened and remember these scary dreams. Nightmares occur mostly during the second half of a night's sleep. They usually relate to developmental challenges, anxiety, and stress. Frequent nightmares may stem from images that stay in their minds after hearing a scary story or seeing a violent TV show or movie. Their nightmares can begin as early as 1 to 2 years of age.