David Harbour is speaking candidly about his personal struggles with mental illness, having been diagnosed with bipolar disorder when he was in his 20s.

“My particular big issue is what society would call mental illness,” the “Stranger Things” star said in an interview with The Big Picture, as reported by Sky News.

“I was diagnosed at 26 as bipolar after an episode that landed me in an institution,” he explained. “I have definitely been in and out of the system. And there were times in my life where very easily I could have ended up on the streets, but I luckily had a family who could support me through those lean and very trying times.”

READ MORE: David Harbour Opens Up About Bipolar Diagnosis In Candid Interview, Admits Acting ‘Is Kind Of A Lifeline’

Because of the stigma surrounding mental illness, Harbour added, it’s an ailment that often goes undiagnosed and untreated, and is particularly exacerbated by poverty.

“It’s not like a broken leg. What defines crazy is social inappropriateness. But it’s very socially inappropriate, in a sense, to not have enough money to live on,” he said.

“Being mentally ill is a natural condition of poverty. When you can’t participate in society by going out buying lunch and go into a store and stuff, it’ll make you crazy,” Harbour added. “It’s chicken and egg. They go hand in hand.”

READ MORE: David Harbour Gets Candid About Bipolar Disorder, Reveals His Parents Sent Him To A ‘Mental Asylum’

The fourth season of “Stranger Things” is streaming now.