"There's too much caffeine in your blood stream and a lack of real spice in your life."—Morrissey

Morrissey is wrong—caffeine can spice up your life. According to a new study, drinking five cups of coffee a day or more was found to be enough to increase a drinker's tendency to hallucinate. 

"High caffeine levels in association with high levels of stressful life events interacted to produce higher levels of hallucination in non-clinical participants, indication that further caution needs to be exercised with the use of this overtly safe drug," said Simon Crowe, a professor at the School of Psychological Sciences at La Trobe University in Australia.

Study participants were assigned to either a high or a low stress condition and a high or a low caffeine condition on the basis of self-report. The participants were then asked to listen to white noise and to report each time they heard Bing Crosby’s rendition of “White Christmas” during the white noise.

The song was never played. The results indicated that the interaction of stress and caffeine had a significant effect on the reported frequency of hearing “White Christmas.” The participants with high levels of stress or consumed high levels of caffeine were more likely to hear the song.

"There is a link between high levels of stress and psychosis, and caffeine was found to correlate with hallucination proneness," Crowe said. "The combination of caffeine and stress affect the likelihood of an individual experiencing a psychosis-like symptom."

This study also helped to explain the mechanism by which stress may facilitate the symptoms of schizophrenia in non-clinical samples. Caffeine has only recently been reported to increase proneness to hallucinate.

"The results also support both the diathesis-stress model and the continuum theory of schizophrenia in that stress plays a role in the symptoms of schizophrenia and that everyone, to some degree, can experience these symptoms," Crowe said. "This was demonstrated by a significant effect of stress on the occurrence of hallucinatory experiences, or hearing the song.

"It is apparent that the health risks of excessive caffeine use must be addressed, and caution should be raised with regards to the exacerbating use of this stimulant," he said.

And that, my friends, is why I stick with tea. 

(Story materials provided by La Trobe University.)