Hallucinations are false or distorted sensory experiences that seem real andmay be seen, heard, felt, and even smelled or tasted, yet are generated onlyby the mind.

A hallucination occurs when a misfire occurs within the mechanism of the brain that helps to distinguish conscious perceptions from internal, memory-basedperceptions. This can be caused by stress, medication, extreme fatigue, mental illness, or other environmental, emotional, or physical factors. Hallucinations occur during periods of consciousness. They can take the form ofvisions, voices or sounds, tactile feelings (touch), smells, or tastes.

Patients suffering from dementia and psychotic disorders such as schizophrenia frequently experience hallucinations. Hallucinations can also occur in patients who are not mentally ill as a result of stress overload or exhaustion, or may be intentionally induced through the use of drugs, meditation, or sensory deprivation. Almost 40% of people are known to experience hallucinations as they are falling asleep. About 12% of people have experienced hallucinations upon waking.

    Common causes of hallucinations include:
  • Drugs. Hallucinogenics such as ecstasy (3,4-methylenedioxymethamphetamine, or MDMA), LSD (lysergic acid diethylamide, or acid), mescaline (3,4,5-trimethoxyphenethylamine, or peyote),and psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine, or mushrooms) trigger hallucinations. Other drugs such as marijuana and PCP have hallucinatory effects. Certain prescription medications may also cause hallucinations. In addition, drug withdrawal may induce hallucinations of sight or touch; as in analcoholic suffering from delirium tremens (DTs).
  • Stress. Prolonged or extreme stress can impede thought processes and trigger hallucinations.
  • Sleep deprivation and/or exhaustion. Physical and emotional exhaustioncan induce hallucinations by blurring the line between sleep and wakefulness.
  • Meditation and/or sensory deprivation. When the brain lacks externalstimulation to form perceptions, it may form hallucinatory perceptions. Thiscondition is commonly found in blind and deaf people.
  • Electrical orneurochemical activity in the brain. A hallucinatory sensation (frequently visual) called an aura often appears before a migraine. Also, auras involvingsmell and touch are known to warn of an upcoming epileptic attack.
  • Mental illness. Up to 75% of schizophrenic patients admitted for treatment report hallucinations.
  • Brain damage or disease. Injuries to the brain may alter brain function and produce hallucinations.

Aside from hallucinations related to waking or falling asleep, more than oneexperience of hallucination suggests a person should see a general physician,psychologist, or psychiatrist to rule out organic, environmental, or psychological causes. If a psychological cause such as schizophrenia is suspected, apsychologist will typically conduct an interview with the patient and the patient's family, and administer one of several clinical inventories, or tests,to evaluate the mental status of the patient.

Occasionally, people who are in good mental health will experience a hallucination. If hallucinations are short-lasting and not frequent, and can be explained by short-term environmental factors such as sleep deprivation or meditation, no treatment may be necessary. However, if hallucinations are hamperingan individual's ability to function, a general physician, psychologist, or psychiatrist should be consulted to pinpoint the source and recommend a treatment plan.

Hallucinations related to a mental illness such as schizophrenia should be treated by a psychologist or psychiatrist. In many cases, chronic hallucinations caused by schizophrenia or some other mental illness can be controlled by medication such as thioridazine (Mellaril), haloperidol (Haldol), chlorpromazine (Thorazine), clozapine (Clozaril), or risperidone (Risperdal). If hallucinations persist, psychosocial therapy can be helpful in teaching the patient the coping skills to deal with them. Hallucinations due to sleep deprivation or extreme stress generally stop after the cause is removed.

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