A mother is awakened in the middle of the night by a terrifying
scream. She races to the room of her three-year-old son, who is
sitting up in bed with tears running down his face, his heart
pounding. The more she tries to soothe him, the more agitated he
becomes. A college student walks into her parents' bedroom while
they are sleeping and pours a glass of water into her mother's
dresser drawer. A physician takes a telephone call from the
emergency room at 3 a.m., receives information about a complex
case, and then gives completely inappropriate instructions for
the patient's care. What all these people have in common is
that, in the morning, none of them remembers a thing. These
stories—all true—are examples of parasomnias, which are defined
as unpleasant or undesirable behavioral or experiential
phenomena during sleep. Abnormal things that can happen to
people while they are sleeping are called parasomnias. Examples
of parasomnias include sleepwalking and night terrors. While
they can be frightening to obse