According to a new study as much as five cups of coffee a day could be enough to make a person develop hearing hallucinations.
For the study the researchers included 92 volunteers who had consumed “high levels” of caffeine thought they were listening to Bing Crosby singing White Christmas, though the song was not being played. They were actually made to listen to a constant fuzzy sound known as white noise. The researchers described caffeine as “the most commonly used psychoactive drug”. They said the study showed that the health risks of too much coffee needed to be addressed.
Professor Simon Crowe, of La Trobe University in Melbourne, said, “We also told them that within the white noise there may be parts of the song White Christmas and if you hear it, press a button. We didn’t include White Christmas in the white noise but found that more people who were very stressed and had high levels of caffeine thought they heard the song. The combination of caffeine and stress affect the likelihood of an individual experiencing a psychosis-like symptom.”
Crowe added, “Caution needs to be exercised with the use of this overtly ‘safe’ drug”
That being said, the findings are consistent with some previous research, according to Dr. Daniel Evatt, a postdoctoral research fellow in the department of psychiatry at Johns Hopkins University School of Medicine, who was not affiliated with the study. In 2009, a survey found that people who drank the equivalent of three or more cups of brewed coffee a day were three times more likely than others to report hearing and seeing things that didn't exist.
Nevertheless, Evatt cautions not to conclude from the current study that caffeine use is generally associated with auditory hallucinations. “For someone to consume a lot of caffeine and experience hallucinations as a side effect is extremely rare…This study is looking more at the processes and using caffeine as a way to understand the processes,” he said. He says these results, which could be replicated with other stimulants like energy drinks, would more likely occur in participants who are already predisposed to having hallucinations.
He explained, “These are interesting initial findings that indicate that stress and a stimulant like caffeine might interact to produce hallucination-like symptoms in some people, but the great majority of the world uses caffeine every day. If people were having full-blown hallucinations regularly, we would know about it.”
The study was published in the journal Personality and Individual Differences.