NEW YORK: Once squeaky clean and baby-faced teen stars, Justin Bieber and One Direction have quickly discovered the harsh realities of living in the public eye.

The young artists each released albums Friday that — while partly staying true to pop formulas that have made them rich — also lay bare their struggles at discovering adulthood at the height of their fame.

“My life is a movie and everyone’s watching,” the 21-year-old Bieber intones near the beginning of his new album, “Purpose.”

“Life’s not easy / I’m not made out of steel / Don’t forget that I’m human / Don’t forget that I’m real,” he sings.

The Canadian singer demonstrates his quest for maturity not just lyrically but musically on “Purpose,” his first album of original work in three and a half years.

Bieber on several tracks — including the album’s early hits “What Do You Mean?” and “Sorry” — plays with a mellow, downtempo tropical house beat, moving away from his typical pop-R&B sound that had done little to distinguish him from other mainstream pop stars.

Bieber, who owes his new sound to LA-based electronic producers Skrillex and Diplo, has banked on “Purpose” to rehabilitate his star power after becoming better known for his off-stage antics than his music since he put out his last album, “Believe,” in 2012.

Among his most infamous non-musical moments, Bieber was caught racing a Lamborghini in Miami Beach while under the influence and without a license.

A judge ordered him to undergo anger management courses for throwing eggs at his neighbor’s home in a glitzy section of Los Angeles, while in Argentina another judge dropped a bid to arrest Bieber for allegedly assaulting a photographer.

On “Sorry,” Bieber offers an apology of sorts. But his regrets appear directed not so much to the world at large but — many fans presume — to ex-girlfriend Selena Gomez, a fellow former teen star and singer.

Bieber teams up with yet another teen sensation turned adult, Ariana Grande, on an acoustic version of “What Do You Mean?” Other collaborators on “Purpose” include rappers Big Sean and Nas as well as Halsey, the 21-year-old electropop singer whose career has seen a meteoric rise.

“Purpose” is not entirely absorbed by introspection. Bieber’s breathy track “Children” consists of unlikely, if unspecific, social activism as he sings, “What about the children? Look at all the children we can change.”

And Bieber’s reflective tone does not necessarily mean he has changed his ways. He recently ended a concert in Norway after one song, apparently upset over fans throwing water, and walked out of a live interview in Spain.

But in an interview with Britain’s New Musical Express, Bieber argued that he had been held to a different standard than other teen stars and said of his life now, “I’m struggling just to get through the days.”