Answered by SecondMedic Expert
Psychiatrist · Psychiatry
You can't really "have" hallucinations. Hallucinations are perceptions in the absence of an external stimulus. They can be caused by many things, including drugs, mental illness, and sensory deprivation.
Most people who experience hallucinations do so because they are taking drugs or they have a mental illness. However, there are some people who can hallucinate without any outside influence by using various techniques to deprive themselves of sensory input. For example, some people will deliberately close their eyes and sit in complete darkness for extended periods of time in order to produce visual hallucinations. Others will listen to white noise or repetitive sounds for long periods of time in order to induce auditory hallucinations.
