Mary Bridget Davies returns to perform in the production ‘One Night with Janis Joplin’ at Arena Stage in Washington, D.C. on June 20, 2013. (Marvin Joseph/THE WASHINGTON POST)

It takes Mary Bridget Davies about an hour to physically become Janis Joplin.

As for the mental and vocal preparation, “it happens throughout the day with me,” says Davies, 34, sitting in her dressing room at Arena Stage. The star of the blockbuster hit “One Night With Janis Joplin,” at Arena for the second summer in a row (“Back by popular demand!”) and heading to Broadway in the fall, is wearing black leggings, a gray T-shirt, and neon pink studded flip-flops. Her long brown hair — which she is contractually obligated not to alter — is wavy and still damp from the shower. “As soon as you wake up and open your eyes, you test your voice to see where you are,” she says.

Davies has been at this for a while. “I was a fan my whole life,” she says. “Screaming along to ‘Piece of My Heart.’ . . . I think every kid who goes through their misfit phase finds Janis.”

When Davies was growing up in Cleveland, she dressed like Joplin for Halloween. This was in the ’80s; her friends thought she was Elton John.

Now Davies has access to the good stuff: costume pieces based on Joplin’s real clothing from Made for Pearl, a clothing and accessories company based in Los Angeles run by Malyn Joplin, the singer’s niece.

‘One Night With Janis Joplin’ by Randy Johnson at Arena Stage. Through Aug. 11. Video courtesy of Arena Stage. (Courtesy Arena Stage/The Washington Post)

“The costumes really help,” Davies says. Slipping into Joplin’s attire, with its bohemian-meets-every-item-in-your-grandma’s-closet-piled-on-at-once look gives you “that force-of-nature feeling. You feel like a sheriff. This unstoppable force. She was so free that anything you have going on in your life, you can bring it to your performance.”

Davies slides into blue jeans with rhinestone-encrusted flared bottoms and zips on heeled black boots. She loops necklaces over her head and bracelets over her wrists by the handful. By the time she’s done, she jingles like a wind chime as she walks, jewelry clinging and clanging with every step. Her posture relaxes, her limbs go loose. She trades her soft Midwestern vowels for Joplin’s Texan twang, a drawl just-so-slurred by drink.

Joplin died of a heroin overdose in 1970 at age of 27, about two weeks after Jimi Hendrix died with the same number of birthdays to his name — everybody knows that part — and Davies acknowledges the shadow that such an exit can cast. But Joplin, she insists, “wasn’t this loudmouth junkie who came onstage and screamed. She was so intelligent. The funniest girl around.”

“She was a raw, visceral nerve. You could feel it in your heart and your fingertips when she sang.”

Davies thinks that the Joplin howl is “part of [my] DNA. I just think that structurally, on a molecular level, I am physically capable of doing this show six times a week. . . . It’s like exercise. Over the years, in my own time and in my own band . . . I’ve laid the foundation to do repeat performances.”

Her natural singing voice is “more soulful” and a bit less scream-y. “I put a lot of the scream and scratch and wail on for Janis, it’s just fun. It feels so good. I know why she did it. It’s cathartic. It’s like therapy, on stage.”

Davies spent her early 20s fronting a blues band in Cleveland (they even changed their name for her, from Blues on Purpose to the Mary Bridget Davies Group) until she joined the national tour of “Love, Janis" in late 2005. She starred in the show on and off for four years and has been performing in “One Night With” since last summer.

Earlier, when Davies was styling (or, more accurately, de-styling) her hair — head upside-down, fingers ravaging her locks from the roots to the tips, blow dryer blaring — she discussed the key to embodying the Joplin aesthetic. She was talking about her hair, but she could have been talking about all of it: the voice, the body, the spirit.

“It has to be as wild and out of control as possible,” she said, flipping her head back up and teasing a few more strands. The end result was everything a fashion magazine teaches women to fix: frizzy, bushy, unmanageable. This was beyond bedhead, past hangover hair. It was a mess. A beautiful mess.

Davies admired her work in the mirror and smiled wide. “There it is.”

One Night With Janis Joplin

Through Aug. 11 at the Kreeger Theater at Arena Stage, 1101 6th St. SW;; 202-554-9066.