Susan Boyle checked out of the Priory this week and into a sparkling €2m London pad with her beloved cat Pebbles. Simon Cowell is believed to be footing the bill.

The 48-year-old church volunteer-turned-global celebrity, whose audition for Britain's Got Talent was viewed by more people than watched President Obama's inauguration, has been wrapped in cotton wool since losing the show's final and cracking from the strain.

Her very public breakdown was no great surprise from a woman who suffers from learning difficulties and had seldom stepped outside her front door before the paparazzi landed on it. But her collapse has sent shivers through the world of reality TV, a media genre whose dark side has come to the fore rather more frequently of late.

At best, Boyle, or SuBo as the tabloids now call her, is suffering from exhaustion. But conscious of how the public on both sides of the Atlantic have taken her to their hearts and felt her plight, the producers of BGT are taking no risks with her welfare, and providing 24-hour pampering to set her on the road to recovery.

Her disturbing demise brutally illustrates the emotional turmoil of reality television and the exploitation of vulnerable people who are barely equipped to take a trip to the shops not to mind cope with the pressures of instant worldwide fame.

In the country that created The Osbournes and Temptation Island, the human fallout from reality shows has sparked debate among some of television's biggest names. Talk show host Larry King has been wondering if the genre is "out of control" and CNN's lightweight Showbiz Tonight is running a series of studio debates about the "many, many shows having a detrimental effect on real life".

The dangers of putting people through the mental strain of reality TV has been further underlined in a new investigation by powerful Hollywood website, The Wrap. It reveals that at least 11 participants on real-life shows have taken their own lives after the search for TV success became too much to bear.

Just months before Boyle became a YouTube phenomenon, 30-year-old Paula Goodspeed, who was ruthlessly rejected by Simon Cowell on American Idol, committed suicide outside fellow judge Paula Abdul's LA home.

Like many would-be performers on reality TV, her audition on the show in 2006 was short and far from sweet. After admitting to spending her childhood drawing life-size pictures of Abdul, she belted out a harrowing rendition of the Tina Turner song Proud Mary leaving the judges sour.

Simon Cowell got personal when he started making fun of the braces on Goodspeed's teeth, asking how any artist "could sing with that amount of metal in their mouths," and joking afterwards as to how she got through the security detectors.

Last November, after taking an overdose of prescription drugs, she was found dead in her car, beside a pile of Abdul CDs and pictures of the star.

The first known suicide of a reality TV contestant took place in Sweden in 1997 when 34-year-old Sinisa Savija hurled himself in front of a train after being thrown off Exhibition: Robinson, a show based on the format for what became the global hit Survivor.

His widow said he simply could not cope with his humiliating exit being broadcast nationwide.

In 2005, a similar fate followed Najai Turpin, a boxer from Philadelphia who shot himself in front of his girlfriend just weeks before The Contender, a US reality series in which he featured, was due to start.

The young boxer had gone back to his ghetto after losing a make-or-break bout and the chance of winning a $1m (€700,000) prize in the Las Vegas final.

NBC, the broadcasters of the multimillion-dollar show presented by Rocky star Sylvester Stallone, said his death had nothing to do with the reality series and that he had undergone extensive mental testing before recording started. But his trainer told a different story claiming he was unable to cope with the pressures of life in front of the cameras.

A successful district attorney chose a similar path in 2007 when she was eliminated from the CBS series Pirate Master. Cheryl Kosewicz, 35, partially blamed the treasure-hunt reality show in a note posted on MySpace before her suicide.

In the same year, Illinois sales manager, Nathan Clutter (26) jumped to his death from a mobile phone tower after he had finished filming on the Fox TV show Paradise Hotel.

In another case, which will go down as one of the most sinister events in reality TV, Texan Deleese Williams had been promised a Cinderella-like transformation by the producers of the series Extreme Makeover. She was told that her deformed jaw, crooked teeth, and small breasts would be a thing of the past once Beverly Hills' finest cosmetic surgeons had got their hands on her.

Her relatives, including her sister Kelli McGee, claimed they were coaxed by the producers of the show to tease her over her looks and point out her flaws, with the apparent intention of contrasting their comments with the made-over Williams.

But the night before Williams was due to have her life-changing surgery, producers sent her home because her recovery time would not fit in with the show's schedule. She left in tears asking "how can I go home as ugly as I left?"

Her return provoked a crisis in the family, who had to confess their real thoughts about William's looks. McGee, already struggling with bipolar disorder, couldn't deal with the guilt and died from an overdose shortly after her sister's homecoming.

In the US, mental health problems among former reality contestants is now so widespread, some psychologists specialise in treating them.

The AfterTV care organisation claims to have more than 800 such patients on its books. Its founder, Dr Jamie Huysman, believes producers are failing in their duty of care to contestants and that the deaths are "just the tip of the iceberg".

"I can think of several more that happened a couple of weeks after TV shows and went completely undocumented," he says.

"At the moment, producers are taking vulnerable contestants and treating them as disposable people. They don't seem to mind, because when someone goes home and dies, it happens off camera."

The apparent link between reality TV and suicide is not just an American phenomenon. In 2007, British Celebrity Big Brother contestant Jo O'Meara attempted to end her life after her fellow housemates called her a bully and a racist in her treatment of the eventual winner Shilpa Shetty.

Last year, the TV series Wife Swap came under fire when one of its subjects Simon Foster was found dead in Brighton after consuming excessive quantities of methadone and alcohol. He had featured on the show because of his alternative marriage arrangements which allowed him and his wife to have girlfriends.

But exposing his bizarre lifestyle ended up backfiring on him. He became a laughing stock in the tabloids, sank into a depression, and lost his job. When his wife took their two children to live with her lesbian lover, he reached his limit and committed suicide.

Susan Boyle's post-final collapse coincides with the new series of Big Brother, or as one commentator put it this week, another batch of fresh meat being fed into the grinder of reality TV. It also follows the disturbing news that the eight babies born to Nadya Suleman, known as Octomum in the US, are to have their every move followed by a documentary-maker's camera.

But producers of the world's most successful and least expensive television genre are quick to dismiss criticism of reality TV and the ethics of using fragile people to boost audiences.

They claim that their star-struck applicants undergo rigorous psychological trials to ensure they can cope with self-exposure and public shaming, but take no responsibility when it ends in tragedy.

But the effectiveness of this testing system is clearly in doubt as so many emotionally damaged people seem to fall through the net, their public meltdowns proving manna from heaven in the ratings game.

Unless TV audiences decide they can no longer stomach the cruelty witnessed week in week out on reality shows and start to switch off, or governments move to ban them, they are certain to go from strength to strength, if recent viewing figures are anything to go by.

- Gemma O'Doherty