Perry, who is working on the play "The End of Longing" in London, appeared on BBC Radio 2 on Friday.
When asked by fellow guest, actor James Nesbitt, about his least favorite "Friends" episode, Perry answered, "I think the answer is 'I don't remember three years of it.'"
He went on to explain:
"A little bit of the time, I was pretty out of it, yeah ... Anyway, my answer to your question is somewhere between seasons three and six."
The actor was admitted to rehab twice during his time on "Friends." He said in a 2013 interview with People magazine that he had already been abusing alcohol when he started the job when he was 24 years old, around 1994, and then became addicted to prescription pain medication after a 1997 Jet Ski accident.
He insisted that he was never "high at work" — just "painfully hungover."
"Eventually things got so bad I couldn't hide it and everybody knew," he said. "I was a hopelessly narcissistic guy, and I only thought about myself, and then that just shifted, and when that happened, I got some true happiness and comfort in my life."
Although Perry couldn't make the "Friends" reunion on NBC's special, "Must See TV: A Tribute to James Burrows," which airs February 21, the actor told BBC Radio 2 that he and the other stars would do a reunion.
"I think the actors would actually be open to it," the 46-year-old said. "We would be open to doing something, some kind of maybe TV special. I don't know about a movie. It's kind of tough, because we ended on such a high note. We don't want to ruin it. So we'd want to be really careful.
Sometimes when you do a reunion, it's terrible and sort of ruins the memory of the good show that you've done before. So we'd have to be careful."