Rob Lowe got sober after he had to go to sleep instead of answering his mother's call about his grandfather suffering a heart attack

He told People: "Getting sober was an incremental decision. It's baby steps until you're ready. You can't do it until you're really ready."

Before he entered rehab at the Sierra Tucson facility in 1990, Rob said he had a series of "baby steps" on the road to getting clean.

He said one of them came when he watched one his "heroes" Warren Beatty in the 1975 romantic comedy 'Shampoo'.

Rob added: "It's a great movie, but at the end, he's a bon vivant, charming playboy left with nothing.

"It affected me tremendously and (was) the first glimmer of your conscience, your destiny, God, going, 'Psst, pay attention to this.'"

Rob added his infamous sex tape of him with two young women was also a major moment in his life.

He said: "(That) definitely changed my life at the time, and, in hindsight, I realised it was another step that led me to recovery and reevaluating my life. "But the thing that really changed me was not being able to show up for my family and myself."

Rob also said in 1990 when his grandfather had a heart attack he ignored his mother's call about the crisis.

He added: "I remember like it was yesterday - my mom telling me (on my answering machine) to 'Pick up, pick up' because my grandpa had had a heart attack.

"I couldn't deal with it in the state I was in, and I needed to go to sleep to wake up so I could deal with it.

"Who doesn't keep a bottle of Cuervo Gold (tequila) by their bedside table? "That was the final wake-up call. I've been sober ever since."