RUTHFULLY YOURS

In “The Anxious Generation,” Mr. Haidt lays out in pitiless detail what happened to the children of Generation Z when life moved online. For this cohort, the first to go through puberty with constant access to the internet, it was not merely that playing and socializing had shifted to phones, tablets and gaming consoles but that real-life pleasures and risks were also disappearing: rough-and-tumble outdoor activities, opportunities for physical independence, unsupervised recreation. Free play had been in retreat and technology on the march since the 1980s, Mr. Haidt observes, but it took the invention of the smartphone, which permits users to be online 24/7, to complete the mutation of childhood from “play-based” to “phone-based.” In words that chill the parental heart, he writes that giving smartphones to young people en masse constitutes “the largest uncontrolled experiment humanity has ever performed on its own children.” The experiment has been a disaster.

Those of us who had middle-schoolers and teenagers in the peak transformative years 2010-15 will remember the bewilderment, the quarrels, the spasmodic madness of that turbulent epoch. Some sons and daughters, like the fictional Caitlin, turned in a matter of months from vivacious participants in their own lives into phone-scrolling automata. Others became volatile, fretting over their “likes” and “followers,” frantically attending to apps that their mothers and fathers only dimly understood: their Instas (public-facing Instagram accounts), their Finstas (the secret Instagram accounts shared with friends) and the streaks on Snapchat that absolutely had to be kept up because it was “a thing.”

To succeed socially on the internet required young people to “devote a large part of their consciousness—perpetually—to managing what became their online brand,” Mr. Haidt avers. “This was now necessary to gain acceptance from peers, which is the oxygen of adolescence, and to avoid online shaming, which is the nightmare of adolescence.”

While all this was happening, parents (who were hypnotized by their phones, too) were hearing about, and sometimes seeing at home, children succumbing to real distress—depression, anxiety, self-harm, even suicide. In the maelstrom it seemed probable that smartphones and social media were playing a role, but parents were hard-pressed to know, exactly, how quantifiable the problem was. Even six or seven years ago, researchers could see that teenagers who spent long hours on their smartphones were more likely to be depressed than teenagers who socialized face-to-face but couldn’t say with certainty that the inputs produced the outcomes.

Now, thanks to Mr. Haidt, we can glimpse the true horror of what happened not only in the U.S. but also elsewhere in the English-speaking world. Starting in about 2010, suicide rates for young adolescents in the U.S. shot up (increasing 91% for boys ages 10-14 and 167% for girls). The rate of self-injury almost tripled between 2010 and 2020. In the U.K., too, more children than before were using self-harm to cope with severe anxiety and depression; in Australia, rates of hospitalization for mental health showed a sharp increase for both boys and girls.

Ironically, the creation of social media—with their promise of “connectedness”—has left young people lonelier and with fewer friends. For girls, the apps have proved toxic, Mr. Haidt writes: “Social media use does not just correlate with mental illness; it causes it.” Boys are less susceptible to the dangers of social media but more vulnerable to the harms of online pornography. Retreating behind their bedroom doors for screen-based virtual lives has put boys at greater risk of malaise, apathy and “failure to launch” into the responsibilities of adulthood.

In the lucid, memorable pages of “The Anxious Generation,” Mr. Haidt, who teaches at New York University and co-wrote “The Coddling of the American Mind” (2018), adopts the old advice about giving a good speech: He tells you what he’s going to tell you, he tells you and then he tells you what he just told you. It’s a bitter read but also a galvanizing one. Having shown how we’ve gone wrong with Gen Z—children born 1997-2012—Mr. Haidt describes how we might spare rising generations the same afflictions.

He advocates schools banning smartphones not only during class time but for the whole school day and giving students more time outside. He recommends that parents limit young children’s exposure to screens (keeping babies away entirely) and delay giving older children smartphones and access to social media until they’ve entered high school. Parents, he argues, should maximize opportunities for their children to exercise autonomy and self-reliance, giving them chores and encouraging them to get real-life experience in real-world, part-time jobs.

At one point in “The Anxious Generation,” Mr. Haidt steps away from his professional persona to write, he says, “as a fellow human being.” Something very deep changed in America in the 2010s, he thinks, and it goes well beyond the realm of child rearing and teenage woe. He has come to believe that “the phone-based life produces spiritual degradation, not just in adolescents, but in all of us.”

Mrs. Gurdon, a Journal contributor, is the author of “The Enchanted Hour: The Miraculous Power of Reading Aloud in the Age of Distraction.”