Delirium affects 70% to 80% of intensive care unit patients and is associated with a 10-fold increase in rates of cognitive impairment at discharge and a 3-fold increase in mortality rates. Estimated costs are $152 billion in Medicare charges annually, 17.5 million inpatient days, and 30-day postdischarge costs of $238 726 per patient. Delirium is an acute disorder of attention and global cognitive function characterized by fluctuating symptoms occurring in the face of an underlying organic cause. As patients adapt to physiological stressors, neurotransmitter changes lead to electroencephalogram pattern changes. The ability to compensate for the chemical (neurotransmitter) imbalances is surpassed, causing the behavioral symptomatology we know as delirium. This article seeks to describe the pathophysiology behind the behavior core to the prevention and management of delirium.