Another is the Survival Rundown which involves repetitive actions like touching a wall - a process that can go on for weeks or months.
The Church of Scientology has spoken out regarding speculation that Jim Carrey's ex-girlfriend, Cathriona White had been a member of the religion.
Just a few days after her body was found at her home in Los Angeles last week after an apparent suicide, it was claimed that Cathriona cold have been involved in "purification" regimes that are part of the religion.
Carrey, 53, had been involved in an on/off relationship with the Irish make-up artist since 2012. The 28-year-old had reportedly been involved in the religion since relocating from Ireland to LA in 2009.
Former members have now alleged the regimes could have had an effect on her mental health.
One regime Cathriona was reportedly involved in, called the Purification Rundown, is a controversial drug and alcohol detox program which combines exercise, medication and reportedly also sees members spending at least four hours a day in a sauna for up to 60 days.
The mother of Scientologist Alexander Jentzsch, who died from a drug overdose in 2012, compared her son's death to that of Cathriona.
Karen De La Carriere, who was a member for over 30 years herself, said: "He did Survival Rundown and the Purification Rundown and at 27 he was dead of methadone and other drugs.
"He died exactly like Cathriona. This is another Alexander, someone also in their twenties and connected with this toxic cult."
The Church of Scientology hit back at the claims. A spokesperson said: "Saying that somebody was studying Scientology in the past and connecting that to a suicide is like saying a person who had previously studied the Bible committed suicide."