for National Geographic News
Double-shot lovers take note—the world's most popular psychoactive drug may have a disturbing hidden effect on some of its habitual users.
Heavy drinkers of coffee, tea, energy drinks, and other caffeinated beverages are more likely to hallucinate, hear imaginary voices, and even sense the presence of deceased people, a new study suggests.
Among the 200 test subjects, those who consumed the equivalent of seven cups of coffee a day were found to be three times more likely to have hallucinatory experiences than those who consumed less than a single cup a day.
Lead author Simon Jones, a psychology Ph.D. student at Durham University in the U.K, is intrigued but cautious about the connection.
"This hasn't shown that caffeine causes hallucinations, though the data are consistent with that idea," he said.
"It could also be that people who have hallucinations are more anxious and worried, so that causes them to consume more caffeine."
Ubiquitous Drug Packs Punch
Caffeine is much loved for its ability to quickly increase alertness, boost energy, and improve mood.
(Read "Caffeine—What's the Buzz?" from National Geographic magazine.)
The massively popular drug's effects have been explored intensely.
Some studies have revealed possible benefits such as relief from pain and headaches and the easing of asthma symptoms.
Others have suggested possible correlations between caffeine use and cancer, fibrocystic breast disease, and osteoporosis.
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