You can’t believe everything you hear, especially if you’re polishing off the third refill of your venti coffee. Australian researchers at La Trobe University have just published a study suggesting that people on a serious caffeine buzz are prone to hear things that aren’t there. The study might raise new concerns about the safety of caffeine. But for the average person who’s weary of conflicting reports about coffee and health, the new findings may not amount to much more than background noise.
Evidently deciding that an actual Starbucks would be too loud for science, the researchers brought volunteers to a lab. The subjects — some highly caffeinated, some not — put on headphones that pumped out white noise. They were told that Bing Crosby’s "White Christmas" would be playing in the background, which was actually just a white lie. Even though Bing wasn’t anywhere around, some of the caffeine-addled listeners said they could hear the song. (In their defense, it should be pointed out that the differences between white noise and "White Christmas" are pretty subtle.) The researchers concluded that five regular cups of coffee could be enough to increase the risk of auditory hallucinations.
The study has some flaws — it was small, it was published in an obscure journal, and it wasn’t well-controlled — but the main finding seems plausible enough. Caffeine certainly can heighten the senses, and there’s growing evidence that it can cause mild hallucinations. A 2009 survey found that people who drank the equivalent of three or more cups of brewed coffee a day were three times more likely than other people to report hearing and seeing things that aren’t there.