Jan. 14 (Bloomberg) -- Consuming the caffeine in seven cups of instant coffee a day may leave you more likely to see, hear and smell things that aren’t there, U.K. researchers said.
People who drink at least 330 milligrams of the stimulant a day were three times as likely to have hallucinations as those who consumed less than 10 milligrams a day, Durham University researchers found in a study of 219 college students published today in Personality and Individual Differences.
The study, the first to link caffeine and hallucinations, explored the relationship between high caffeine consumption and an increased release of cortisol, a stress hormone believed to contribute to delusions, lead researcher Simon Jones said. It forms the first step toward examining nutrition as a factor in the occurrence of hallucinations, he said.
“Given the link between food and mood, and particularly between caffeine and the body’s response to stress, it seems sensible to examine what a nutritional perspective might add,” Jones said in a statement.
It may also be that people under stress and more susceptible to hallucinations are also more likely to consume high levels of caffeine, Jones said in an interview. Caffeine is also contained in tea, chocolate, energy drinks, and some foods.
“There would be no real reason for me to stop drinking tea,” said Jones. “I don’t see a reason to change a moderate intake.”
Starbucks
The amount of caffeine linked to hallucinations in the study would also be equivalent to about seven 8-ounce cups of brewed black tea or about 3 1/2 8-ounce cups of brewed black coffee, according to the Mayo Clinic Web site. One 16-ounce Starbucks Corp. drip coffee also has 330 milligrams of caffeine, according to the Starbucks Web site.
Starbucks spokeswoman Tara Darrow declined to comment in an email, saying the Seattle-based company was aware of the research but hadn’t been able to review how it was conducted.
The U.K. researchers used surveys to assess daily caffeine intake and past experience with hallucinations. Cigarette smokers, known to be more sensitive to caffeine, weren’t allowed to participate, and volunteers’ stress levels and proneness to hallucinatory experiences were taken into account.
Nine of the 22 people in the highest-caffeine group reported hearing disembodied voices, compared with three of the 22 people in the lowest-caffeine group, Jones said. Participants also reported seeing things that weren’t there and sensing the presence of dead people.
To contact the reporter on this story: Naomi Kresge in Zurich at nkresge@bloomberg.net
Last Updated: January 14, 2009 08:57 EST
