Workers who find themselves reaching for that extra cup of coffee on a stressful day may find themselves hallucinating in the office.
La Trobe University research found that stressed coffee addicts are three times more likely to see or hear imaginary things than everyone else.
The study tested 92 people with varied caffeine intake and stress levels. Subjects were played Bing Crosby’s song White Christmas. They were then played three minutes of static hiss and asked to press a buzzer if they heard snippets of White Christmas.
The low-caffeine subjects heard it once, while stressed coffee drinkers buzzed three times on average, even though the song was never played.
"If you are stressed and have a high level of caffeine, you are more likely to notice things that aren't there, see things that aren't there," said Professor Simon Crowe, who ran the study.
Crowe said about 15% of the population reported hallucinatory or delusional experiences, things such as hearing voices or their own thoughts, seeing ghosts, or sensing telepathy.
In an office environment, a caffeinated worker would be on edge and may not correctly interpret situations, he said.
"For instance, they may (mistakenly) believe that someone around the water cooler is talking about them and they will tend to overreact."
Crowe said 80% of the world's population had a daily caffeine fix. But, while we are aware of the risks of drugs such as amphetamines, we are less concerned by coffee.