Around 3% of people are thought to hear voices when there is no one talking.
People who drink a lot of caffeine — over 7 instant cups of coffee a day — have triple the risk of hallucinating, research finds.
Hallucinations can include hearing voices when no one is talking and seeing things that are not there.
Those who had high caffeine intake were three times more likely to report these experiences, along with sensing the presence of dead people.
The reason could be that caffeine boosts the production of the ‘stress hormone’ cortisol.
Too much cortisol may cause people to hallucinate.
Dr Simon Jones, the study’s first author, said:
“This is a first step towards looking at the wider factors associated with hallucinations.
Previous research has highlighted a number of important factors, such as childhood trauma, which may lead to clinically relevant hallucinations.”
The study asked 200 people about any hallucinatory experiences and their caffeine intake from products like energy drinks, chocolate bars, tea and coffee.
Dr Charles Fernyhough, who co-authored the study, said:
“Our study shows an association between caffeine intake and hallucination-proneness in students.
However, one interpretation may be that those students who were more prone to hallucinations used caffeine to help cope with their experiences.”
Dr Jones said:
“Hallucinations are not necessarily a sign of mental illness.
Most people will have had brief experiences of hearing voices when there is no one there, and around three per cent of people regularly hear such voices.
Many of these people cope well with this and live normal lives.
There are, however, a number of organisations, such as the Hearing Voices Network, who can offer support and advice to those distressed by these experiences.”
The study was published in the journal Personality and Individual Differences (Jones & Fernyhough, 2008).
