Deprive coffee addicts of their morning fix and you will soon hear about it. But give them too much caffeine, and it turns out they will be the ones to start hearing things.
In the latest addition to the pile of research papers published on the bitter brown elixir, scientists have found that drinking five or more coffees a day is enough to increase a person’s tendency to hallucinate. Caffeine lovers with high-stress lifestyles are most at risk.
The study, published in the journal Personality and Individual Differences, measured the effect of stress and caffeine on 92 people. The participants were grouped according to self-reported stress levels and caffeine consumption. Those drinking five or more standard caffeinated drinks a day were classed as high caffeine users.
Participants were then asked to listen to white noise and to report when they also heard part of Bing Crosby’s White Christmas coming through the white noise. The song was never played, and researchers measured the number of false alarms reported.
Those in the high-stress, high-caffeine group reported hearing the song three times as often as those in the low-stress, low caffeine group.
Those with a low stress but high caffeine lifestyle reported the song 40 per cent more often than the low-stress, low caffeine group.
”The combination of caffeine and stress affect the likelihood of an individual experiencing a psychosis-like symptom,” said the study’s lead author, Simon Crowe, a neuroscientist at La Trobe University in Victoria.
Professor Crowe said the mental health risks associated with excessive caffeine use need to be addressed.
”We have a safe drinking guideline for alcohol but we don’t have a safe caffeine guideline even though caffeine is a stimulant drug,” he said.
Kane Browning, a barista at Toby’s Estate Coffee in inner-city Sydney, said the cafe had a number of customers who drink more than five cups a day. ”There’s one guy who sits there with all these espressos lined up,” he said.
Three of Mr Browning’s customers yesterday – Tom Thorburn, Luke Kneller, and Toby Miles – all admitted to drinking five or more cups of coffee every day.
But none of them could remember experiencing hallucinations.