Caffeine and Hallucinations?

We learned in class that caffeine is a stimulant, but a new study shows it may have some hallucinogenic effects, summarized in this article.

Researchers at Durham University conducted a survey among "high caffeine users" and found correlation to stress and proneness to hallucination.
Before the implications are discussed, we first must note the definition of these "high caffeine users." The study defines it as "more than 7 cups of instant coffee a day," which, because I think instant coffee is gross, I had to do some research for. According to the USDA, instant coffee averages around 100mg of caffeine. To put it into my perspective, that's 3-4 cups of regular, brewed coffee. And even less cups of espresso. (Check out conversions for your caffeinated-beverage-of-choice here. Bear in mind serving size; they are all for 8oz.)

What I thought the article tried to get at but failed to make clear was this: Caffeine, stress, and sleep deprivation all contribute to cortisol levels, a hormone produced in the adrenal gland, and widely dubbed "the stress hormone." So the so-called chicken-egg situation should be more like a cycle--people aren't taking in caffeine because they hear voices. Rather, these people are under a lot of stress to perform well, thus have to stay up late to study thus can't sleep, thus drink coffee. All of these factors combined spell cortisol release. And it is cortisol that causes the hallucinations.

I searched for the actual study to see if this was discussed (the link in the article didn't work) and found access to the abstract. Even when stress was controlled for, caffeine still succeeded to produce proneness to hallucination, but not 'persecutory ideation'--when an individual believes that harm is occurring or going to occur, when in fact no harm is present.

In the end, while caffeine intake, stress, and sleep deprivation are all positively correlated and lead to cortisol increases, which in turn can lead to hallucinations, elevated caffeine-intake alone is enough.

- Emily Rogers