"I thought I was going to overdose almost every time," Alley says. "I would snort the coke, then I would sit there, I'd take my pulse [thinking], 'I'm dying, I'm dying, I'm dying.' Who would keep doing it?"
Alley tells Chris that a Scientologist friend prompted the actress to read Dianetics, which the former Cheers star says she sometimes read while snorting cocaine.
"Somehow I got through [the book], and I thought either [Scientology] is the world's biggest scam or I thought this is how I am going to get rid of this hideous compulsion," says Alley.
For more of Alley's interview, tune in to ET tonight, Wednesday, November 7.