Tom Cruise is a strong advocate of this treatment -- co-founding the New York Rescue Workers Detoxification Project, which uses L. Ron Hubbard's "purification rundown" principals for those exposed to toxic chemicals after the terrorist attacks of 9/11.
"When I started this project, it was because I was in a position where I knew that I could help," Cruise said at a project event.
Scobee had the treatment.
"When I did it the first time... it was one week..., and I felt, brighter and more alert," she said. "My skin was, you know, vibrant and stuff like that."
But far away from the limelight of celebrities, Scobee says the program can also be used to discipline Church staff members. She says she was once told to take part in a purification rundown that ended up lasting eight months.
Scobee: I was at 5,000 milligrams of Niacin for months and months. I don't know what that did to my body! (Laughs). I have no idea.
Nightline: How did you feel?
Scobee: I felt really, there was like gray stuff coming out of my skin, and I didn't know if it was like my insides coming out (laughs) or whatever that long of being in the sauna five hours a day every day.
Nightline: Five hours?
Nightline: And you kept going?
Nightline: What happened when you did it for eight months?
Scobee: That was when I, uh, decided I didn't want to be there anymore ... to satisfy somebody else's demands on ... on me, to fix me, because of their preconceived ways.
The Church denies Scobee's characterization and says the program is a "religious service," and to claim it as a "kind of perverse punishment" is "gross in the extreme."
Perhaps the most sensitive aspect of the Church's theology concerns confidential scriptures meant only for higher level Scientologists.
According to former Church insiders, these documents describe L. Ron Hubbard's belief in an intergalactic emperor called Xenu who brought the spirits of his people to earth 75 million years ago, burying them in volcanoes. These spirits, the story goes, have stuck to the bodies of people living today in the form of "body thetans."
"They have had some really bad experience millions, billions, trillions, actually quadrillions of years ago, which is way older than the Big Bang basically...," said Bruce Hines. "You're supposed to, isolate ... and communicate with them telepathetically, so that they go away."
Tommy Davis spoke with "Nightline."
Nightline: Do you believe that ... a galactic emperor called Xenu ... brought his people to earth 75 million years ago and buried them in volcanoes?
Nightline: Do you believe that?
Davis: Martin, I am not going to discuss the disgusting perversion of Scientology beliefs that can be found out commonly on the Internet and be put in the position of talking about things for ... that ... talking about things that are so fundamentally offensive to Scientologists to discuss...
Nightline: Well, I ... I have the burden of my own journalistic responsibility ...
Nightline: ... that I bring to this meeting and I hope that, I've been appropriately respectful of you in my asking of the questions ...
Davis: Well, you haven't to the degree that the question that you asked me you know, by virtue of the fact that it's been made very clear in other media entities that it's something that we consider offensive ... It is in violation of my religious beliefs to talk about them.