Nightmares are unpleasant or frightening dreams that occur sporadically in virtually all children. The peak incidence occurs between 3 and 6 years of age. Developmental, genetic, psychological, and organic factors have been identified as causes of nightmares. Nightmares usually occur in the middle of the night or in the early morning when rapid eye movement sleep is more common. The content of the nightmare almost always involves a specific danger to the child. On awakening, the child is fully alert, may be easily calmed or comforted, and can usually recall the details of the nightmare. Sporadic nightmares are common in children and require reassurance only. If nightmares are frequent and persistent, a psychological evaluation of the child and family is indicated.