HO CHI MINH CITY - An's folly was League of Legends, a fantasy fight game that consumed her for 18 hours a day until she joined a school for troubled teens which features the real-world hard knocks of Vietnam's homegrown martial art.

With no phone or console and 5:30 am wake-up calls, the 16-year-old initially struggled to adjust to the rigors of life at the boarding school on the outskirts of Ho Chi Minh City.

She also didn't take to Vovinam, the acrobatic, high-kicking martial art created in the 1930s by borrowing elements of kung fu and other Asian disciplines.

But she had little choice.

An is among around 300 teens at the Research Institute for Vovinam and Sport Development, or IVS, where the physical and emotional control demanded by Vovinam is used to wean kids off screens and addictions to booze and drugs, and to ease depression.

After a few dark weeks, An - full name Tran Nguyen Nhat An - finally started to emerge from her malaise.

"I was just depressed, in my room. I never exercised, I never talked to anyone ... here I can talk to everybody," she said, wearing her blue two-piece Vovinam uniform as classmates sparred on mats nearby.

"I practice (Vovinam), exercise, so my health is getting better. Maybe that's helping my emotions getting better too."

Millions of youngsters like An are glued to online gaming in Vietnam, where some 30 percent of the population of 93 million have smartphones and about half have internet access.

League of Legends and Dota are favorites, especially among the booming population of under-30s.

Though no nationwide official data on gaming addiction exists, pediatric psychiatrist Lam Hieu Minh says he's seen a rise in visits from kids hooked on screens.