The actress admitted her spell in treatment wasn't what many stars experience when they seek help for addiction issues and emotional problems today as her rehab was "a very severe lockdown" facility.

"(It was) no Hollywood rehab, 30-day, Malibu beachside bulls**t," she explained. "This was school of hard knocks in the most severe way, and I'm 13 to 14."

But the Charlie's Angels star insists she's glad she stayed the course and stuck rehab out, adding, "I swear to God it's what I needed. I had nothing but freedom up until that point, partying it up, doing whatever I wanted..."

The actress spent 18 months in the "institution", and admits her first weeks there were a real wake-up call.

"All of a sudden, it was, 'You have no freedom, you will figure out your life', and it was so upsetting at first, but over the course of that year and a half... I left there the most humble person you can ever imagine."

Then, as her voice quivered, Barrymore thanked the counsellors who helped her get her life in order.

"They save my life," she said.