Nightmare

A nightmare, also known as a bad dream, is an unpleasant dream that can provoke a strong emotional response, typically fear but also despair, anxiety, disgust or sadness, and may contain situations of discomfort or psychological or physical terror or panic; afterward a person often awakens in a state of distress and may be unable to return to sleep for a time, and recurrent nightmares may require medical help since they can disrupt sleeping patterns and cause insomnia. Nightmares can have physical causes, such as sleeping in an uncomfortable position or running a fever, or psychological causes such as stress or anxiety, and eating before sleep, which raises the body's metabolism and brain activity, can also be a potential stimulus. Their prevalence in children aged five to twelve is between twenty and thirty percent, and in adults between eight and thirty percent, and in everyday language the word nightmare has extended metaphorically to describe many other unpleasant things, such as a bad situation or a frightening person.