Many patients admitted to ICU experience hallucinations. These hallucinations can be very distressing and frightening for people.
Most commonly, people report disturbing dreams, or vivid hallucinations whilst awake. Many patients who experience hallucinations on ICU do not consistently recognise the hospital environment, and therefore experience their surroundings as hostile or threatening (e.g., hallucinations of distorted faces, animals, staff trying to harm patients, being kidnapped, having been arrested, etc.). Patient may understandably become very distressed and agitated when they experience hallucinations, as in that moment, the brain perceives the hallucination as a real representation of the environment.
Hallucinations on ICU occur due to a condition called delirium. Delirium is a symptom of critical illness and is caused by multiple factors, including the underlying condition that led to the admission to ICU, medication, the environment, and metabolic changes in the body. Early symptoms of delirium (such as a sudden onset of confusion, changes in speech, agitation, and restlessness) are often already present before a patient is admitted to ICU, and can become exacerbated during the ICU admission. Some patients develop delirium whilst they are on ICU. For some patients, symptoms of delirium can continue after discharge from ICU, and it may take some time to fully recover from delirium.
It is important for both patients and families to understand that ICU hallucinations are not a symptoms of mental illness. Many patients worry about disclosing their experience of hallucinations due to concerns that they have developed a mental health condition. ICU hallucinations and ICU delirium are medical conditions, and directly linked to the critical illness. Understanding the cause and signs and symptoms of delirium can often be reassuring for patients.
Many patients will continue to have very clear memories of their ICU hallucinations and may continue to have disturbing dreams or flashbacks of them. For many patients, being able to understand delirium can help to make sense of the experience, but some patients may require additional therapeutic support after being discharged from ICU.