A nightmare, also called a bad dream,is an unpleasant dream that can cause a strong emotional response from the mind, typically fear but also despair, anxiety and great sadness. The dream may contain situations of discomfort, psychological or physical terror or panic. Sufferers often awaken in a state of distress and may be unable to return to sleep for a small period.
Nightmares can have physical causes such as sleeping in an uncomfortable or awkward position, having a fever, or psychological causes such as stress, anxiety, and as a side effect of various drugs. Eating before going to sleep, which triggers an increase in the body's metabolism and brain activity, is a potential stimulus for nightmares.
Recurrent nightmares may require medical help, as they can interfere with sleeping patterns and cause insomnia.