Have you ever heard a song when none was playing, clearly seen someone’s face when no one was there or felt the presence of a person, only to turn around to an empty room? If you’ve consumed a lot of caffeine—the equivalent to seven cups of coffee—you are three times more likely to hear voices than if you had kept your caffeine intake to less than a cup of coffee, according to psychologists at the University of Durham in England. Their recent study shows that overingesting the stimulant slightly increases your risk of experiencing other hallucinations as well.
Caffeine heightens the physiological effects of stress, lead author Simon Jones says. When someone feels anxiety, the body releases the hormone cortisol, and when people drink plenty of caffeine-infused tea, coffee or soda, their body produces more of the hormone when they encounter stressful events. Researchers have proposed that cortisol may trigger or exaggerate psychotic experiences by increasing the amount of the neurotransmitter dopamine flowing into the brain’s limbic areas, evolutionarily ancient regions involved in emotion, memory and behavior.
“The prevalence of hallucinations is probably greater than people would expect,” Jones says. Research shows that every year about 5 to 10 percent of people—many of whom do not suffer from mental illness—experience delusions such as hearing voices and seeing things that are not there. According to Jones, “a range of people have frequent hallucinations yet cope well with these experiences.”
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More research needs to be done before we can directly attribute hallucinations to caffeine; it is possible that people who already see, hear or feel these illusions may be consuming more caffeine for some other, as yet unknown reason, such as self-medication. Jones and other scientists also plan to look at whether nutritional influences such as sugar and fat might play a role in triggering phantom sights and sounds.
Note: This article was originally printed with the title, "Coffee Breakdown."