Demi Moore’s life changed on a dime, she says, the day she had to “revive” her mother from a drug overdose. She was only a child at the time.

While promoting her upcoming memoir, the ‘Ghost’ and ‘Striptease’ actress got candid with ‘Harper’s Bazaar’ about growing up with a father who she later discovered was not her biological parent and a mother struggling with substance abuse.

“I remember ... using my fingers, the small fingers of a child, to dig the pills my mother had tried to swallow out of her mouth while my father held it open and told me what to do,” Moore, 56, said in the magazine’s October issue, where she spoke with fellow actress Lena Dunham. “Something very deep inside me shifted then, and it never shifted back. My childhood was over.”

Moore also reflected on her own battles with addiction and her-off-and-on relationship with sobriety. Throughout her fluctuating career, the former Mrs Ashton Kutcher has found herself making headlines for substance abuse, but said she now finds solace in staying clean.

“In retrospect, what I realised is that when I opened the door (again), it was just giving my power away,” she said.

“I guess I would think of it like this: It was really important to me to have natural childbirth because I didn’t want to miss a moment. And with that I experienced pain. So part of being sober is, I don’t want to miss a moment of life, of that texture, even if that means being in ... some pain.”

Moore’s book, ‘Inside Out’, hits shelves in the US on September 24.