'Reality TV is to blame for a rise in psychiatric problems where the sufferers become convinced their own lives are being played out in front of the cameras, experts say.
The phenomenon has been dubbed Truman syndrome, after hit movie The Truman Show, in which Jim Carrey plays the unwitting star of a lifelong reality show.
Psychiatrist Ian Gold said reality TV shows such as I'm A Celebrity..., with their ability to turn strangers into intimates, may add critically to the psychological pressure on people who already have underlying problems.
Dr Gold, a philosophy and psychology professor at McGill University in Montreal, Canada, stressed that he was not saying reality shows made healthy people delusion, but added: 'At the very least, it seems possible to me that people who would become ill are becoming ill quicker or in a different way.'
Researchers in London described a Truman syndrome patient in the British Journal of Psychiatry in August.
The 26-year-old postman 'had a sense the world was slightly unreal, as if he was the eponymous hero' in The Truman Show, the researchers wrote.
In the 1998 movie, Carrey's character Truman Burbank leads a largely uneventful life until he realises his friends and family are actors, his home town is a sound stage and every moment of his life has been broadcast on television.
His struggle to sort out reality and illusion is often horrifying for Truman syndrome patients, researchers say.
Dr Joel Gold (no relation), a psychiatrist with New York's Bellevue Hospital, said he encountered five patients with delusions related to reality TV in the space of two years. Several of them specifically mentioned The Truman Show.
One man showed up at a U.S. government building asking to be released from the reality show he was sure was being made of his life.
Another was convinced his every move was secretly being filmed for a TV contest.
A third believed that everything - the news, his psychiatrists, the drugs they prescribed - was part of a fake stage-set world in which he was the involuntary star.
Dr Gold added that while it was not unusual for psychiatrists to see delusional patients who believe their relatives have been replaced by impostors or who think figures in their lives are taking on multiple disguises, Truman delusions are more sweeping, involving not just some associates but society at large.
He said: 'The question is really: Is this just a new twist on an old paranoid or grandiose delusion ... or is there sort of a perfect storm of the culture we're in, in which fame holds such high value?'
But other researchers are not convinced of the effects of the Truman syndrome.
Psychologist Vaughan Bell of King's College London said one of his former patients believed he was in the virtual-reality universe portrayed in the 1999 sci-fi blockbuster The Matrix.'