Sometimes, late at night, long after his parents have drifted off to sleep, Kieran White stares out his bedroom window and agonizes about the future.

Kieran, 13, imagines his father hooked up to a ventilator, incapacitated. He sees himself by his father’s side, lifting him into a wheelchair.

“It’s like my mind turns into a roller-coaster ride,” he said. “And I feel like life is going by too fast and I don’t have enough time to be a kid.”

In many ways, Kieran lives a typical teenager’s life — riffing on an electric guitar, practicing martial arts with friends, and catching his father in chokeholds and hugs.

Yet there is a side to Kieran’s life that his friends and teachers seldom see.

In June 2012, Kieran’s father, Bob White, 51, was diagnosed with ALS, better known as Lou Gehrig’s disease. The incurable condition is gradually destroying the neurons that control his movements, and has forced Kieran into a part-time role as a child caregiver.

Kieran’s mother, Argerie, an adoption specialist from Costa Rica, does most of the housework and helps Bob dress and shave in the morning, among other tasks. But it’s too much for one person, and some of the care inevitably falls to Kieran.

Many mornings, the seventh-grader helps his father bathe. When Kieran returns home from school, he assists with his father’s physical therapy, moving his arms and legs back and forth as he lies outstretched on the family couch. There are countless other tasks, from pushing his father around the neighborhood in his wheelchair to shifting the gears of the family’s Toyota sedan so his father can back out of the driveway.

“I don’t know what we would do without Kieran,” said his father, who worked as an international sales manager before ALS made him too weak. “He is a blessing.”

Kieran sometimes seems to relish his role as man of the household. One afternoon in April, he stood proudly atop his family’s one-story house in West St. Paul after cleaning muck from the gutters, a job his father used to do. As neighbors watched, Kieran stretched his arms like Leonardo Di Caprio in “Titanic,” and shouted over the streets below, “I’m the king of the world!”

But his teenage bravado often gives way to sadness and anxiety. When his classmates talk of high school or college, Kieran, a straight-A student, feels uncomfortable. Any mention of the future conjures up images of his father even weaker — or gone entirely. Kieran has seen the statistics: 60 percent of ALS patients die within two to five years of their diagnosis.

“I do my best to live in the present, because the future is so uncertain,” he said.

Once a week, Kieran meets with a social worker in the basement of his school. Mostly, they talk about life and music while playing Uno, a colorful card game. But it’s also a chance for Kieran to share his thoughts and anxieties without having to bother his parents. He says they already have enough to worry about.

“The other day, we were talking about college and stuff, and I was saying that, like, maybe there will be a cure by then,” Kieran told the social worker. “And my dad, and this was probably a joke, but he said, ‘And maybe by then I’ll be dead.’ And my mom was really angry at him for saying it.”

“Did that make you mad, too?” asked the social worker.

Kieran pondered the question awhile before shaking his head. “No, no. My dad, he’s just trying to show me the reality,” he said. “And I have to face it.”