Definition

A mental state in which a person is confused and has reduced awareness of their surroundings. The person may also be anxious, agitated, or have less energy than usual and be tired or depressed. Delirium can also cause hallucinations and changes in attention span, mood or behavior, judgement, muscle control, and sleeping patterns. The symptoms of delirium usually occur suddenly, last a short time, and may come and go. It may be caused by infection, dehydration, abnormal levels of some electrolytes, organ failure, medicines, or serious illness, such as advanced cancer.