The movie is based on the play of the same name, which tells the story of a visitor who turns an evening upside down when he interrupts a gathering of gay men in New York City in 1968. It's set a few months before the Stonewall riots - a series of spontaneous, violent demonstrations by members of the gay community in response to a police raid that began at New York's Stonewall Inn - and the difficult nature of some of the scenes required Matt do some "purging" once he'd finished filming.
Matt, who also starred in the Broadway run of the play in 2018, told Britain's The Guardian newspaper, "At the end of the play each night there's some closure. You've purged. Whereas on film, you have time to go home and overthink. It's this lingering experience that bubbles up throughout the shoot. Sometimes with films I need to do something ritualistic to bring the experience to a close once it's finished."
Asked for an example by the interviewer, Matt replied, "Oh, it will all sound too esoteric and strange. I'd rather keep it mysterious than make it corny."
The 42-year-old came out publicly in 2012 and admitted that "certain things" changed for him after he revealed his sexuality.
"Certain rooms I used to frequent - suddenly the door was closed. But I also engaged with artists who don't care, who just want the actor they believe is best for the role, and those are the artists I wanted to be working with anyway so I don't count it as any kind of loss," he insisted.
"The Boys in the Band" will be released on Netflix on 30 September.