Jan Smith doesn’t sleep a lot.

Time, she says, is her “personal monster,” but one that she tackles with the same ferocity as everything in her life.

She’s known in the industry as “Mama Jan,” the frank-yet-empathetic vocal coach who has become a star because of her high-wattage clientele: Usher, Rob Thomas, Justin Bieber, Drake, The Band Perry and Young Jeezy are just a handful of her multi-platinum charges.

She had a prominent role in Bieber’s 2011 concert documentary “Never Say Never,” spending 86 dates on tour with the teen idol and frequently dispensing blunt advice about his vocal care. Usher publicly gushes about her — he claims to have nicknamed her “Mama Jan,” but Smith says it was Atlanta singer-songwriter Jeffrey Butts “and Usher drove it home.”

Now Smith, 56, a singer-songwriter-musician since her teens, is adding another job to her resume – production and artist development.

“It was just a natural progression,” she said in her Southern lilt while seated in a purple-hued recording room at Jan Smith Studios, a 4,500-square-foot suite tucked inside a non-descript building off Briarcliff Road.

The first artist she signed to her Homegirl Entertainment is Alex Hall, a 19-year-old country rocker from Gainesville, whose debut video, the patriotic “You’ll Need an Angel,” arrived Memorial Day weekend.

The unfailingly polite Hall, who has been honing his songwriting skills in Nashville, admits that his voice needed some guidance when he first started working with the woman he affectionately refers to as a “drill sergeant.”

“I didn’t know anything about singing. I just sang and Mama Jan taught me about the vocal cords being an instrument. She knows how to push me to those limits without pushing me too far. We’re a lot alike and perfection is one of those ways that we are,” Hall said.

Along with Hall, Smith is developing Revel in Romance, a young trio of sophisticated rockers from Alpharetta, and has recently been in training with the von Trapps, the four great-grandchildren of Capt. and Maria von Trapp of “Sound of Music” fame. Smith also works with Alpharetta sister act Von Grey and last year brought both Von families together to sing “Crying Bloody Water” for a video circulating on YouTube.

Those are the burgeoning stars. Meanwhile, a wall in the front room of Smith’s working lair – which has been expanded in the past decade to include seven studios and nine teachers – is blanketed with photos of Top 40 hitmakers and luminaries such as Will Smith, Ray Charles, Jimmy Jam and Diane Warren.

Fans of those familiar faces view Smith as a conduit to their music idols – hence her more than 300,000 Twitter followers – but the singers who have developed under her tutelage regard her as an invaluable friend and instructor, even after they’ve reached mega-stardom.

Since 2010, the country sibling trio The Band Perry – Kimberly, Reid and Neil Perry – has been ubiquitous on the charts with No. 1 hits “If I Die Young,” “All Your Life,” “Better Dig Two” and “Done.”

Smith served as Kimberly’s first manager with the Perry parents when the fledgling singer was in her late teens (Artist management, however, is not in Smith’s future – “I don’t want the phone calls at 3 a.m. that the bus broke down,” she said.) and remains tight with the band.

“The first time I came into (Jan’s) studio she had me sing ‘Happy Birthday,’” Kimberly recalled. “She told me I was the most vanilla-white singer she had ever heard, but she knew there was a soul singer in there.”

Kimberly’s younger brothers remember sitting in on their sister’s sessions with Smith and “hearing these animal sounds coming out of the studio,” Reid said.

“She has a wonderful way of making you understand the physical side of singing,” Kimberly said. “It’s very important to her that artists maintain a spiritual balance.”

Usher was in his late teens when he came to Smith. She worked with him in the early days of his “My Way” and “8701” albums and then she “really kicked his butt” for three months before he recorded “Confessions,” the 2004 follow-up that sold 10 million-plus copies and launched him into the stratosphere.

“That made a tremendous difference to everybody else’s ear in the progression of him as a superstar singer, and I’m proud because that’s my work with him,” Smith said.

Of the hundreds of acts Smith has coached, she pinpoints Usher as “the single most gifted singer I’ve ever worked with in 26 years.

“He’s a remarkable vocal specimen and he understands it now,” she said.

Smith only caught his judging stint on “The Voice” a few times – much work, not much sleep, remember? – but said with a smile, “I hear my ‘isms,’ every time he opens his mouth … and he always gives me credit.”

Another famous Smith product is Grammy-winner Rob Thomas, lead singer of Matchbox Twenty. They met 18 years ago — Smith praises him as the “first major artist to put me on the map” — before he began work on the band’s debut album, 1996’s “Yourself or Someone Like You,” which sold 12 million copies.

“Rob didn’t come into the game thinking he was a great singer because he was a songwriter,” Smith said. “But he’s become a great artist because he was willing to study his own art form and his own vocals to make himself a better live performer.”

To this day, Thomas uses a warm-up tape from Smith before every live performance.

“She’s a blues singer herself, so I think she has an affinity for rock ‘n’ roll voices,” Thomas said. “She understands the life of being on the road. She’s had her own pitfalls and she never looks down on anyone in judgment.”

The “pitfalls” that Thomas refers to include Smith’s decade-long affair with her married keyboard player. She reflects on that, as well as her Christian faith, in a collection of essays she published in 2009 called “Run the Other Way.”

“I’ve made a lot of mistakes,” she said. “While I’m not sorry for that, I learned a lot from it and it taught me a lot about my own shortcomings. In 2000, God redeemed my life.”

She also struggled with drug addiction that landed her in rehab in the early ’70s.

“I’ve been hung over a toilet. I get it. I’ve done more illegal drugs than most of my clients who come in here,” she said. “That’s not my life anymore, but I think for that reason (artists) trust me and I can speak from a place of truth and non-judgment.”

An Atlanta native who grew up attending Southern Baptist churches with her parents James and Betty, Smith started singing at age 3 in the “Angelic Choir” at First Baptist Church in Forest Park. By age 9, she learned to play the ukulele and wrote her first song. The guitar followed at 10, and her first studio recording five years later. Highly regarded for her fiery blues-rock voice, she performed in rock bands through high school, college and early adulthood. But when she was 30, she helped restore the voice of a fellow singer who was destroying his throat with rock ‘n’ roll excesses.

“I knew the walk,” she said, “so I gave him suggestions of things that could make him better. And from there, all this was born.”

Smith still sings every day — usually when working with students — and performs “when I want to and need to.” In May she popped up at the Red Clay Theatre in Duluth to participate in a benefit concert for Canton-based SERV International. She’s also compiling new songs for an eventual recording. But, she says with a wry smile, “I’m old enough now to know that Clive Davis ain’t gonna come knock on my door and say, ‘I’m going to make you a star.’”

Despite her maternal moniker, Smith has never married and doesn’t have children, but in her way, she’s helped birth scores of talented, thriving singers.

Smith expresses deep gratitude for her success – “I think I live a very charmed life to be able to do what I do,” she says several times in slightly altered forms during the course of a conversation – but beyond that is her genuine love of the game.

Seeing an artist such as Alex Hall stand on stage and win an award or achieve a hit record would “be the be all, end all,” she said.

And she is adamant that there is no desire to leave Atlanta or pursue a life that doesn’t include music.

“If I won the lottery tomorrow, I might take a little more time off,” Smith said, then paused and laughed. “Maybe charter a plane and take some of my best friends to lunch in France. But I would still be back here, doing what I do.”