1 in 20 People Has Hallucinated

Jun 11, 2015

by Rachael Rettner

About 1 in 20 people in the general population has experienced at least one hallucination in their lifetime that wasn’t connected to drugs, alcohol or dreaming, according to a new study.

Researchers analyzed information from more than 31,000 people in 18 countries who were interviewed as part of a mental health survey from the World Health Organization. Participants were asked whether they had ever heard voices or seen things that didn’t exist, or if they had experienced a delusion (a false belief), such as the thought that their mind was being controlled or that they were being followed.

The study excluded people who possibly had a psychotic disorder, such as schizophrenia or manic depression, which can cause hallucinations and delusions. Therefore, the findings show that hallucinations and delusions are not always connected to serious mental illness, the researchers said.

“We used to think that only people with psychosis heard voices or had delusions, but now we know that otherwise healthy, high-functioning people also report these experiences,” study co-author Dr. John McGrath, a professor at the Queensland Brain Institute in Australia, said in a statement.


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23 comments on “1 in 20 People Has Hallucinated

  • I had a period of a about a year when every strange thing I had ever conceived or read is a science fiction book came to life. In movies, hallucinations come with a foggy/wavering special effect to let you know this is not real. Real hallucinations come with no such warning. It is extremely difficult not to treat them as reality, since they look identical to reality, other than being strange. Part of the hallucination is other people agreeing with you about the weird thing that just happened. The best handling I have seen in a movie is Beautiful Mind where the audience is similarly confused about what is real and what is hallucination.



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  • I think a distinction has to be made between hallucinations that the person believes (albeit only momentarily) and hallucinations that are recognized immediately as physiological glitches. In the latter category would be the auras that come with or without migraine, and the internal sounds that are associated with some forms of epilepsy. A mentally healthy person who knows a bit about physiology and is not religious would recognizes those events as biological, but might still use the word “hallucination.” I guess I’m taking issue with the word, since it does not distinguish between trivial body events and the belief in the reality of the experience. Perhaps it would simply be better to say, “brain misfirings are common human experiences, and pathologies (or social problems) arise when the patient assumes the vision/sound to be real.”



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  • justinesaracen
    Jun 12, 2015 at 2:56 am

    A mentally healthy person who knows a bit about physiology and is not religious would recognizes those events as biological, but might still use the word “hallucination.”

    Years ago, I had a hallucination of being levitated off the bed and floating, but I put it down to running a high temperature and being full of medication!



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  • A mentally healthy person who knows a bit about physiology and is not religious would recognizes those events as biological

    Back in the days of the burning bush, I can imagine a person experiencing the hallucination would have been terrified. Hallucinations, like rainbows and almost every other unexplained phenomena where put down the gods. I can understand this back then, but to continue today, is unforgivable. A burning bush talking? Angels? Ewan’s moment of rapture?

    brain misfirings are common human experiences,

    This is all you need to know.



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  • Alan I attended a talk here in the UK by Brian Sharpless. He’s an assistant professor of psychology and director of the Psychology Clinic at Washington State University. From what I gather based on what he was talking about, you’re describing what sounds like a form of sleep paralysis. This can sometimes feel like you’re floating or being pulled in a certain direction. Varying hallucinations (waking dreams) can occur but not always. This can be very scary but is perfectly harmless. It has been used as anecdotal evidence to prove anything from demonic harassment to alien abduction! It can be induced by stress, medication, or even just happen without.



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  • David R Allen
    Jun 12, 2015 at 7:02 am

    Back in the days of the burning bush, I can imagine a person experiencing the hallucination would have been terrified.

    There is perhaps another explanation of the gob-smacked, staring at “the burning bush” in wonderment!

    https://en.wikipedia.org/wiki/Dictamnus

    Dictamnus is a genus of flowering plant in the family Rutaceae, with a single species, Dictamnus albus, which has several geographical variants.[2] It is known variously as burning bush, false dittany, white dittany, gas plant and Fraxinella. It is an herbaceous perennial, native to warm, open woodland habitats in southern Europe, north Africa and much of Asia.

    In the summer months, the whole plant is covered with a kind of flammable substance, which is gluey to the touch, and has a very fragrant, lemony aroma; but if it takes fire, it goes off with a flash all over the plant. The name “burning bush” derives from the volatile oils produced by the plant, which can catch fire readily in hot weather, leading to comparisons with the burning bush of the Bible, including the suggestion that this is the plant involved there. The daughter of Swedish botanist Carl Linnaeus is said to have ignited the air once, at the end of a particularly hot, windless summer day, above Dictamnus plants, using a simple matchstick.



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  • It’s just an interesting fact. But…..I think it is important for people to learn that their brain has limits and is flawed. We trust our “experiences” without questioning their validity and reality. Many make inferences from analogies that are far from the truth – see a hallucination, do we then accept it without scrutiny?



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  • We all know our perceptions are reconstructed after the event by a memory which has all manner of filters and biases put upon by the unconscious parts of our brains which does most of our processing.
    Studies into perceptions and cognition show we are more than capable of “conjuring up” things that do not exist under a variety of circumstances such as heightened emotion,fear, stress etc. In the past ergot poisoning was frequent cause of hallucinations.
    It is our experience of reality that is tentative and uncertain and not to be wholly trusted. This is why personal testimony is not worth listening to on subjects of magic.



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  • Therefore, the findings show that hallucinations and delusions are not always connected to serious mental illness, the researchers said.

    I think there is another possible interpretation. I think the whole concept of mental illness as currently defined is problematic. There are almost definitely some conditions such as schizophrenia that are fairly well defined and have unambiguous symptoms such as hearing voices. But for many of the most common diagnoses: bipolar, ADD, autism, the possible symptoms are all over the map. At a minimum a better understanding of the mind and brain will eventually invalidate these but I think what is also likely is that we will come to realize that being depressed or manic or obsessive, etc. aren’t symptoms of a disease they are part of being alive. Some of us have some behaviors more than others but the whole notion, for example that we should treat someone who is depressed the same way we treat someone who has cancer or the flu is I think going to eventually be discarded.



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  • Sensory deprivation of any kind, or simple monotony in one’s environment or situation, can cause hallucinations. “White line hypnosis” suffered by long-distance drivers at night, the lack of sleep and monotony endured by long-distance sailors, sleep deprivation in night-shift workers – all can cause hallucinations. It’s not a symptom of mental illness – it’s just fatigue, boredom, and a repetitive, non-stimulating environment. Did the study take these situations into account? How many people hallucinate when NOT fatigued, bored, or sensory-deprived?



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  • My husband has been diagnosed as bipolar, and it is definitely not a vague or ill-defined set of symptoms that are “all over the map”. A diagnosis of bipolar disease must meet certain well-defined criteria, such as a clear episode of major depression (a state in which the person cannot function in his normal environment) that lasts at least two weeks, followed or preceded by a clear state of mania or hypomania. Mania includes extreme insomnia, hyperactivity, lack of judgment, euphoria and grandiose ideas, forced and pressured speech, flight of ideas, and can escalate to psychosis. My husband’s depressions were so severe that he had to be hospitalized to be fed, or he would have starved himself. He did not eat, talk, or get out of bed, and lost nearly 50 pounds during one episode. It wasn’t just a period of “the blues”. His manic symptoms included extreme agitation, insomnia (going without sleep for several days), talking non-stop at high speed while jumping from topic to topic with no sense of coherence or relevancy (pressured speech), constant state of physical activity including extreme endurance exercise (daily bike rides far exceeding his normal mileage), starting but not finishing dozens of projects, and spending extravagant amounts of money on anything that struck his fancy. He progressed to frank delusions and hallucinations. Anti-psychotics, a combination of anti-depressant and anti-epileptics used as mood stabilizers have helped, but he still needs frequent dosage adjustments and regular follow-ups with his psychiatrist to keep him functional. His episodes are completely unrelated to his social, financial, job or family circumstances or environment – a clear indicator of an organic disease process that has nothing to do with ordinary emotional “ups and downs”.

    Bipolar disease is not a fashionable disease of the week that is being diagnosed in everybody who has a few ups and downs. It is a real and devastating brain disorder, and minimizing it just adds to the stigma that people with mental illness face. Please don’t do this. Depression and bipolar illness are the leading cause of suicide. Non-existent diseases don’t cause people to kill themselves. Anti-depressants may be overprescribed by physicians to people who don’t really need them, but that does not mean that mental illnesses like depression and bipolar disease aren’t just as “real” as schizophrenia.



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  • There is a form of repetitive hallucination known as Charles Bonnet Disease. It can be visual or auditory and has nothing to do with schizophrenia or any mental illness. It’s a result of visual or auditory sensory deprivation and usually occurs in elderly people who’ve gone partially blind or deaf. It’s as if the parts of the brain that process sight and sound can’t deal with a lack of input and start putting on their own show. Sufferers immediately recognize that the things they see and hear are not real, though. Oliver Sacks wrote a wonderful book about it called – appropriately – “Hallucinations”. In the book he also details an experiment in which neurology students presented at various mental facilities, pretending to be suffering from hallucinations. They were immediately diagnosed as schizophrenic, even though they lacked the other positive and negative signs and symptoms of schizophrenia.



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  • I occasionally have auditory hallucinations, and it takes me a while to figure out that the music I hear is not coming from a TV or neighbor’s party. It usually happens at night, and the music is clear but distant, loud enough to be distracting or disturbing, and fades in and out. My doctor told me it’s a common form of tinnitus or “ringing in the ears” that’s perceived as music instead of the usual high-pitched ringing that most people get. I’ve learned to plug my ears when it happens. If I can still hear the music, it’s not real. I can sometimes get rid of it by listening to speech, like movie dialogue or talk radio. White noise doesn’t work. My brain tries to pick out any rhythm or cyclical sound, and turns it into music.



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  • “We used to think that only people with psychosis heard voices or had delusions, but now we know that otherwise healthy, high-functioning people also report these experiences,” study co-author Dr. John McGrath, a professor at the Queensland Brain Institute in Australia, said in a statement.

    Perhaps this is just the media taking their usual approach to science reporting where everything has to be an overturning of previously held dogma. I blame Kuhn and his bloody paradigm shifts. But if not it is strange that a professor at a Brain Institute hasn’t read Oliver Sachs book Hallucinations

    http://www.amazon.com/Hallucinations-Oliver-Sacks/dp/0307947432

    One of the clear messages of that book was how common hallucinations are. Although if my memory serves me correctly hallucinations like in that picture are less common.

    Interesting read by the way.



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  • …perceived as music instead…My brain tries to pick out…

    Fascinating. Would love to hear a sample, were it possible and with your permission of course.

    A shame humans can’t “mind-meld” brain experiences – e.g. sharing a dream-bite in lieu of attempting to describe it, an exercise in frustration it is. Beware, in the wrong hands could be hacked and shared.



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  • The study didn’t mention religion. Perhaps it wasn’t considered relevant.

    To psychiatrists religion is very important, clinically.

    Religious delusions are found in at least a quarter of all psychotic states, according to Siddle, Haddock, Tarrier & Faragher, 2002. There is no specific form or content difference between spiritual and psychotic experiences, but convention permits discriminating one as an illness while regarding the other as normal. You can read some of this online – Psychology, Religion, and Spirituality, James M. Nelson, Google Books.

    Isabel Clarke’s ‘Discontinuity Model’ has furthered our knowledge into the overlap between psychosis and spirituality. She put it thus: “Psychosis and spirituality both inhabit the space where reason breaks down, and mystery takes over. For me as a psychotherapist working with people with psychosis, this encounter poses questions: questions such as; “Why is religious/spiritual preoccupation and subject matter so prominent in psychosis?”



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  • Just FYI.

    At least one famous musician experienced similar. Became an expert musician partly to get hold of and compose and perform this music.
    I don’t recall exactly who. It’s a well-known British rock guitarist with a recent-ish autiobiography. Most likely Pete Townsend, but may have been Andy Summers, Keith Richards, or Eric Clapton – all very interesting autobiographries.



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