Hallucination

A hallucination is a perception in the absence of external stimulus that has qualities of real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. They are distinguishable from several related phenomena, such as dreaming, which does not involve wakefulness; pseudohallucination, which does not mimic real perception, and is accurately perceived as unreal; illusion, which involves distorted or misinterpreted real perception; and imagery (imagination), which does not mimic real perception and is under voluntary control.

Types of Hallucinations

Hallucinations can affect any of the senses (visual, auditory, olfactory, gustatory, and tactile) and hence, can be categorized as follows:

• Visual hallucinations: Seeing objects, people, or events that are not actually present.
• Auditory hallucinations: Hearing voices or sounds that do not exist. This is the most common type of hallucination in people with psychiatric disorders like schizophrenia.
• Olfactory hallucinations: Smelling odors (usually unpleasant) that are not actually present.
• Gustatory hallucinations: Tasting things that aren't there.
• Tactile hallucinations: Feeling physical contact from an object or person that does not exist.

Causes

Hallucinations can occur for various reasons and can be a symptom of a number of conditions, including:

• Mental illnesses such as schizophrenia, bipolar disorder, and severe depression.
• Neurological conditions such as dementia, migraines, epilepsy, and brain tumors.
• Use or withdrawal from certain drugs, including recreational drugs like LSD or medical drugs like prednisone.
• Extreme stress or lack of sleep.
• Certain types of vision or hearing loss can lead to hallucinations (Charles Bonnet syndrome, musical ear syndrome).

Treatment

Treatment for hallucinations involves addressing the underlying cause. This can range from medication for conditions such as schizophrenia or bipolar disorder, to therapy for conditions like depression or anxiety, to lifestyle changes in cases where the hallucinations are due to stress or lack of sleep.

See Also

• Delusion
• Psychosis
• Schizophrenia
• Visual snow

Hallucination Resources
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