The crackdown has begun. That’s the message Jared Cramer, a father in Virginia, is sending to his 13-year-old daughter, Julia.

Cramer made national news this month when he decided that he was going to lock Julia out of her own closet until she paid him back the $541 in cell-phone charges she racked up in a single month. By doing chores around the house, Julia, whom news outlets report is an otherwise good student and a kind person, plans to eventually regain access to her clothes and accessories.

Jared seemed pretty pleased with his no-nonsense plan.

“She thought after I got that bill it was going to be a slap on the wrist, you know, ‘don’t let it happen again’ type deal.”

Indeed, for years, parents have been faced with shocking bills associated with their kids’ phone use. Whether it’s “in-app purchases” or simply data usage, kids have no concept of what their activities are going to cost.

In a recent commercial for a fixed-rate data plan, two mothers chat about how their kids are constantly on their phones, while their kids sit in front of them each glued to a screen.

In May, Katie Dupuis, managing editor at the magazine Today’s Parent, wrote about how she recently got a message on her cell phone saying she had used up all her data for the month. As it turns out, it wasn’t Dupuis, it was her 2-year-old daughter, whom she describes as an “iPad/iPhone junkie.”

Dupuis assures readers that she realizes this is a “serious sign,” and she and her husband are planning to curtail the girl’s screen time. But how has it come to this?

Why is it only when kids’ digital activities start to affect their parents’ bottom line that anyone seems to take notice? Why does it take a message from AT&T to tell you that your toddler is spending more time in front of a screen than her parents are?

Like many parents, Dupuis has found the iPad very useful. She commutes in “wall-to-wall rush hour traffic” to and from day care every day and “an electronic puzzle makes that a little less painful for all of us.” But at what cost?

There has long been talk about the effects of looking at a screen on our ability to do other things. Any parent can see what spending too much time on an iPad does to a child’s attention span.

We even see it in ourselves. We can’t stay on one screen long enough to read an 800-word column. We’re checking our phones when we’re supposed to be reading a book or doing some other kind of work.

The switch from a medium that provides immediate gratification to one that doesn’t is hard — and it’s even harder for kids.

But now experts are seeing a whole range of new problems that arise from screen time. Adam Cox, a clinical psychologist working mostly with children, says he regularly sees patients who complain of headaches and stomach pain when they’re not in front of a screen. “Kids are translating boredom into physical distress.”

Watching a show or even doing an electronic puzzle on a screen doesn’t provide the same kind of mental downtime that, say, reading or even looking at a picture book might. Reading books, Dr. Cox says, allows “moments of pause and reflection.” But games on screens just “crank up the stimulation.” The constant screen time gives kids the impression that “every day is a big roller coaster.” It would be hard to go back to ordinary life after that.

Cox says that all the time our kids spend on devices also affects how we treat each other. He describes a loss of civility between parents and children. Kids who come into his office with their parents can’t look at him, can’t look at them. They can’t sit for even a minute without going to grab their parents’ devices.

Lowell Monke, an emeritus professor at Wittenberg University, has lectured extensively on issues of technology, particularly in schools. Monke, who has taught computer engineering to high-school students, is no Luddite, but he sees the attachment to devices as not only undermining interpersonal relations, but also the way people interact with nature and even the way they interact with machines.

Monke laments that kids today are so busy on screens they don’t get around to looking at insects or climbing trees or tinkering with tools and figuring out how things work.

Which brings us back to the real problem with shelling out $541 for a child’s cell-phone bill. Money is time. Time that kids aren’t spending on being kids.

Naomi Schaefer Riley is a senior fellow at the Independent Women’s Forum.