The Moneyball star, 48, who was nominated for Best Actor at the Academy Awards, said his fame had caused him depression.
In an interview with Hollywood Reporter magazine he revealed: “I got really sick of myself at the end of the 1990s.
“I was hiding out from the celebrity thing, I was smoking way too much dope, I was sitting on the couch and just turning into a doughnut and I really got irritated with myself.
“I got to: ‘What’s the point? I know better than this.’ I was doing the same thing every night and numbing myself to sleep — the same routine: Couldn’t wait to get home and hide out. But that feeling of unease was growing and one night I just said, ‘This is a waste.’”
He said trips to Yugoslavia and Morocco in the late 1990s were a wake up call, showing him “poverty to an extreme I had never witnessed before”.
He said: “I just quit. I stopped grass then — I mean, pretty much — and decided to get off the couch.”
Pitt mett Jennifer Aniston in 1998, and the pair married in 2000. They divorced five years later.
The star also spoke about his brood of six children with Angelina Jolie, revealing that they hadn’t seen their parents’ movies.
He said: “They understand Mommy and Daddy work in stories and work in movies and they understand movies just for that.
“I want them to find them on their own when they’re a bit older and I can see what they mean to them then.”
Pitt is up for the Best Actor Oscar alongside his pal George Clooney, as well as Jean Dujardin, Gary Oldman and Demian Bichir.
George Clooney is no stranger to depression either – he admitted to considering suicide after being injured while making the film Syriana.