Five or more coffee a day was found to be sufficient to increase the tendency for participants to have hallucinations, says Simon Crowe, a professor of psychology at La Trobe University. Hallucinations are false perceptions that an individual must not exist. For example, a person can hear, see or smell things that are not there.


Crowe and colleagues at the School of Psychological Sciences measured the effect of stress and caffeine with 92 nonclinical participants, according to a La Trobe. Participants were assigned to a high or a low voltage condition and a high or a low state of caffeine on the basis of self-report. They were then asked to listen to white noise and to report whenever they heard Bing Crosby version of “White Christmas” in white noise.

White noise is a type that is produced by combining sounds of all different frequencies together, like the white light produced by a combination of seven colors. The song was never played. The results indicated that the interaction of stress and caffeine has a significant effect on the reported frequency of hearing “White Christmas“.

Participants with high levels of stress or high levels of caffeine consumed were more likely to listen to the song. “The combination of caffeine and stress affect the probability of an individual experiencing a psychotic symptom

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