Trauma Survivors Network - provided by ATS

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Delirium or Sundowning

Definition and Overview

Delirium can be used to describe a rapid decline in focus, perception, attention, and cognition. Delirium is not a disease but a syndrome, meaning that it describes a set of symptoms. There have been many terms to describe the spectrum of cognitive impairment known as delirium, and these include ICU psychosis and sundowning. It is a very common disorder affecting up to 20% of hospitalized adults. It can often be unrecognized or diagnosed, being mistaken for dementia, old age, schizophrenia (hallucinations), or other mental impairment. 

Causes and Symptoms

Most types of mental illness, medication, or intoxication could cause delirium, and it occurs more easily in people that are already suffering brain dysfunction. Common causes include substance intoxication or withdrawal, hypoxia, hyperglycemia, hyperthermia, infection, brain lesions, postoperative stress, malnutrition, closed head injury, organ failure, vitamin deficiency, shock, and heart failure.

The most common symptoms of delirium include reduced awareness, focus, and ability to sustain or shift attention. There is usually some type of memory impairment or change in perception by the patient and sometimes hallucinations occur. The onset of the syndrome commonly takes hours to days. The course of the illness is short, lasting only a few days to weeks, and is often reversible. 


The treatment for delirium usually includes supporting the patient with fluids and food, as well as providing a comfortable environment with plenty of support. Most properly cared for patients will recover with no lasting problems.