The “fake scientific study” of the day is the one that announced that four cups of coffee would make you see visions.

It got a lot of press, of course, with even the staid National Geographic reporting “Coffee may cause hallucinations”.

The UK press had a field day:

Three cups of brewed coffee a day ‘triples risk of hallucinations’. The Daily Telegraph, January 14 2009

Go easy on the coffee, you could start seeing things. Daily Mail, January 14 2009

Coffee link to ‘visions’. Daily Mirror, January 14 2009

‘Visions link’ to coffee intake. BBC News, January 14 2009

When I first read the stories, and found the study was in college students, the first thing I thought of was sleep deprivation, something that is often associated with both coffee and high stress during “all nighters” before exams.

Of course, 40 plus years ago, when I was a college student, amphetamines and Ritalin weren’t controlled substances, and were commonly used with the coffee to stay awake, so we did know of students who saw things after too many all nighters, and everyone back then knew how to “cure” them: Give them a joint and let them “crash”.

So presumably the students were screened for drug use, right?


And you checked if the hallucinations were not due to other “recreational” substance,right?

Wrong. The only “drug” the scientists screened for was cigarettes.

And you checked that the hallucinations happened at a time when they were using a lot of (legal) caffeine, right?

Wrong again.

The doctors did an elaborate analysis that correlated the self reporting level of caffiene with hallucinations, making the report look oh so scientific:

For every milligram increase in daily caffeine intake per kilogram of bodyweight (equivalent to an extra 1.5 cups of instant coffee for an 11-stone person), there was only an increase of 0.18 on the hallucination score (this score can range from 0 to 64, with a higher score indicating greater level of hallucinations).

But the study is actually an example of “Garbage in, Garbage Out” type of scientific study.

First of all, they didn’t use a typical population.

The “study” was mainly of 20 year old women

Nor did they ask the participants to keep a diary about their coffee/caffiene/beverage usage: the scientists only asked them how much coffee/caffeine they used on the average each day.

Not only does the intake vary from day to day in most people, but the amount of caffiene in coffee or tea varies greatly with how it is brewed.

The scientists then gave the students a test which  included questions about hearing voices or seeing things or people who weren’t there…but included things like vivid daydreams as positive for hallucinatory episodes.

the scale used measured “hallucination proneness” rather than strictly “hallucinations”, and it includes assessment of what most people might consider “normal” experiences. For example, one of the areas assessed includes having vivid daydreams…

But what was missing was the time relationship between caffiene intake and the hallucinations.

Did they bother to ask: When you heard voices/saw a vision, had you consumed more coffee than usual?


Did they bother to ask: What was the circumstances of the hallucinatory episode?


Did the hallucination come after an all nighter? (sleep deprivation can cause hallucinations)?


Did they ask: Was it during your period? (Women having their period often increase their coffee intake due to fatigue, and NSAIDs and other pain killers can cause hallucinations.) Were you pregnant when you hallucinated? Or did you recently have an abortion? (Hormone changes can affect mood, and pregnancy can induce severe stress).

Women under stress tend to get more headaches, including migraine headaches. Migraine headaches can be associated with a visual aura that could be reported as a hallucination on their testing.

So were the students screened for such medical problems?



and No.

Did they ask: Were you depressed, and using caffiene to help relieve the fatigue of depression? (Depression can cause hallucinations).


And, of course, the big question:

Were the hallucinations visual or auditory?

Most lay people think a hallucination is a hallucination, but actually, most “psychotic” hallucinations (e.g. schizophrenia, depression with secondary psychosis, or other mental illnesses) hear voices.

Schizophrenics often drink a lot of coffee, as do those depressed, in an attempt to “self medicate”.

In contrast, visual hallucinations are more common with epilepsy, dementia, sleep deprivation or drugs.

Finally, do the students come from a culture where visions or mystical experiences are common?

Most people won’t talk about such things, for fear of being labeled “crazy”, but I suspect they are more common than some scientists realize. In one study:

Greeley and McCready found that 27% of participants in a national survey in the USA replied in the affirmative to the question: ‘Have you ever felt that you were really in touch with someone who has died?’

Despite these obvious flaws in the study, the scientists, based on a study of only 200 students, mainly female, mainly college students, and using crude self reporting data, nevertheless made elaborate computations with it, and gots lots and lots of publicity with their bad experiment.

And the reporting on the study is even worse, since the scientists merely noted an increase in hallucinatory phenomenon was statistically correlated with a higher ingestion of caffeine, but the news reinterpreted the study as “causing” the hallucinations.

Nancy Reyes is a retired physician living in the rural Philippines. Her website is Finest Kind Clinic and Fishmarket, and she writes medical essays at HeyDoc Xanga blog.

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