Prevalence and Types of Hallucinations

Prevalence and types of hallucinatory experience

Studies have now shown hallucinatory experiences take place across the population as a whole. Previous studies, one as early as 1894[1], have reported that approximately 10% of the population experience hallucinations. A recent survey of over 13,000 people[2] reported a much higher figure with almost 39% of people reported hallucinatory experiences, 27% of which reported daytime hallucinations, mostly outside the context of illness or drug use. From this survey, olfactory (smell) and gustatory (taste) hallucinations seem the most common in the general population.

Hypnagogic hallucinations and hypnopompic hallucinations are considered normal phenomena. Hypnagogic hallucinations can occur as one is falling asleep and hypnopompic hallucinations occur when one is waking up.

Auditory hallucinations, particularly of one or more talking voices, are particularly associated with psychotic disorders such as schizophrenia, and hold special significance in diagnosing these conditions, although many people not suffering from diagnosable mental illness may sometimes hear voices as well.[3] The Hearing Voices Movement is a response to the Psychiatric interpretation of auditory hallucination. Other types of auditory hallucinations include musical hallucinations, where people will hear music playing in their mind, usually songs they are familiar with. This can be caused by lesions on the brain stem, occurring most often from strokes, but also tumors, sencephalitis, or abscesses.[4] Recent reports have also mentioned that it is possible to get musical hallucinations from listening to too much music.[1] Florid hallucinations are usually associated with drug use (particularly hallucinogenic drugs), sleep deprivation, psychosis or neurological illness.