June 10, 2011 at 2:37 PM ET
If you're hearing voices in your head, you may want to cut back on the caffeine. A recent Australian study showed a link between heavy coffee consumption, stress -- and auditory hallucinations.
Here's what happened: The volunteers listened to white noise played through a computer's headphones for three minutes. Every time they heard even a snippet of Bing Crosby's White Christmas, they were told to press a hand tally counter. (They weren't aware of the real point of the study -- they were told it was about auditory perception.)
The song was never played. But the participants who said they were very stressed, and very caffeinated -- those who regularly drank five or more cups per day, at 200 milligrams of caffeine each -- were more likely to imagine they'd heard it.
"We believe that high stress, in addition to taking high levels of caffeine, makes people yet more stressed and thus makes them more likely to 'overreact' to the environment -- i.e., to hear things that just aren’t there," explains Simon Crowe, the lead author of the study and a neuroscientist at Australia's La Trobe University, located in Bundoora, Victoria. The report was published in the April issue of the journal Personality and Individual Differences
It's worth noting here that there are some limitations to the study: The levels of stress and caffeine consumption were both self-reported by the 92 volunteers who participated in the experiment. And what if, somehow, the caffeine-stressball combo made participants more eager to try to please the researchers -- yes, of course we heard the song! It's lovely, isn't it?!
Then again, maybe that's just what the voices in my head are telling me.
How much caffeine do you consume each day?
Follow Melissa Dahl on Twitter: @melissadahl.