People have hallucinations for the following three common reasons: 1, physiological hallucinations, which are extremely rare, mostly seen in normal people who have sleep paralysis, and often have more vivid hallucinations when they are about to wake up, including auditory hallucinations and visual hallucinations; 2, mental illnesses, mental illnesses commonly have various hallucinations, including auditory hallucinations, visual hallucinations, thought chirps, thought echoes, etc., mainly seen in schizophrenia, and A kind of stress-related mental disorders and hysterical psychosis, mainly psychogenic hallucinations, and strong mental stimuli are related; 3, organic mental disorders, mostly seen in some important organs of the brain damage such as the frontal lobe, temporal lobe, limbic system, these parts govern the higher emotions, cognitive functions and mental behavior, when damage occurs, it is easy to produce organic mental disorders, including visual hallucinations and auditory hallucinations. Visual hallucinations and auditory hallucinations are the most common.