A couple of months ago, my 15-year-old daughter admitted she was addicted to her phone and that she hated it. She deleted TikTok and asked me to buy her a timed lockbox so she could take breaks from her smartphone—and also asked for a flip phone so she could still stay in touch when she was taking time off. I happily obliged. But the pit in my stomach about her being a phone addict—and about how she still struggles daily to stop herself from scrolling and from actually using the lockbox—has not dissolved.

It’s why the gospel of Jonathan Haidt, social psychologist at NYU Stern School of Business and author of The Anxious Generation: How the Great Rewiring of Childhood Is Causing an Epidemic of Mental Illness, resonates so deeply—not only with me, but with the tens of thousands of devotees who have kept his latest book on the New York Times bestseller list for 12 weeks and counting. (Which is not to say he hasn’t faced much pushback, which he has.)

Inspired to get to the bottom of the teen mental illness epidemic, which he says began around 2012, and encouraged by the findings of other social scientists including San Diego State University’s Jean Twenge (author of iGen), he looked toward years of correlational, longitudinal, and truly experimental studies—all kept track of publicly. And the book, in summary, concludes that we as parents have overprotected our children in the real world but have under-protected them online, and that it has to stop in order to nurture the mental health of our kids.

And the best path toward this, as he lays out in his book, is to follow four “foundational” rules to “provide a foundation for healthier childhood in the digital age.”

Below, the rules, with context.

1. No smartphones before high school

“Parents should delay children’s entry into round-the-clock internet access,” Haidt, the father of two teens, writes, “by giving only basic phones (phones with limited apps and no internet browser) before ninth grade (roughly age 14).”

“Millennials went through puberty with flip phones, and flip phones aren’t particularly bad. You use them just to communicate,” Haidt told ABC News. “It was when we gave kids smartphones, and then right around that time they also got … social media accounts. When kids move their social lives onto social media like that, it’s not human. It doesn’t help them develop. And right away, mental health collapses.”

While speaking at the Wall Street Journal’s Future of Everything Festival in May, he added: “You do not give a child the internet in their pocket, where strangers can reach them and they can watch beheading videos.”

Bill Gates, for one, agrees. And at least 60,000 U.S. parents kind of agree: They have signed a pledge through the campaign Wait Until 8th, which aims to empower parents to rally together in waiting until eighth grade, just a year earlier than Haidt recommends, to get their kids smartphones.

So when do kids tend to get their first smartphone? According to research by Common Sense Media (2021), 42% of U.S. kids have a phone by age 10—and by age 14, smartphone ownership climbs to 91%.

2. No social media before 16

“Let kids get through the most vulnerable period of brain development before connecting them to a firehose of social comp and algorithmically chosen influencers,” Haidt stresses in his book—adding at the WSJ festival in May: “Don’t let children go through puberty on social media, that’s the really vulnerable time.”

U.S. Surgeon General Vivek Murthy, who last week called for social media platforms to come with a warning label, pointed out in his 2023 advisory that up to 95% of youth ages 13 to 17 report using a social media platform, with more than a third saying they use social media “almost constantly.” And although age 13 is commonly the required minimum age used by social media platforms in the U.S., he noted, nearly 40% of children ages 8 to 12 use social media. And besides, Murthy said in a CNN interview, “personally, based on the data that I’ve seen, I believe that 13 is too early.”

He added, “If parents can band together and say, you know, as a group, we’re not going to allow our kids to use social media until 16, or 17, or 18, or whatever age they choose, that’s a much more effective strategy in making sure your kids don’t get exposed to harm early.”

3. Phone-free schools

As Haidt writes in his book, “in all schools from elementary through high school, students should store their phones, smartwatches, and any other personal devices that can send or receive texts in phone lockers or locked pouches during the school day. That is the only way to free up their attention for each other and for their teachers.”

Because, as he noted at the WSJ event, “imagine, for those of you who went to school before the internet, imagine that the school had a new rule: You can bring in your television from home, you can bring in your walkie-talkie, you can bring in your record player, put it all on your desk, we’ll give you an outlet, and you can do that during class while the teacher’s talking. This is complete insanity. But that’s what we’ve done.”

Instead, when schools let kids keep the phone in their pocket, he added, “you have to hide it behind a book or under your desk if you want to text and watch video and watch porn, which the kids do.”

Earlier this month, the board of the Los Angeles Unified School District—the second largest school district in the country—approved a total ban on phones at school, set to take effect by the spring 2025 semester. In Massachusetts, more than half of districts have a total ban on phones at school. In New York, as Gov. Kathy Hochul considers a statewide ban, leaders of New York City public schools—which lifted a phone ban in 2015—say a full ban will return in 2025.

4. Far more unsupervised play and childhood independence

That’s the way children naturally develop social skills, overcome anxiety, and become self-governing young adults.

“There can’t be an adult guarding them all the time until they go to college,” Haidt said at the WSJ event.

He credits at least some of his epiphanies around this issue to Free-Range Kids founder and advocate Lenore Skenazy, famously dubbed “World’s Worst Mom” in 2008 when she wrote about letting her 9-year-old take the New York City subway home alone. Haidt joined Skenazy in founding Let Grow, which advocates through legislation and school programs for childhood independence.

On the New York Times’ Hard Fork podcast in March, he elaborated on this fourth rule: “My story is not a simpleminded story about it being all smartphones and social media. It’s actually a two-part story about the decline of the play-based childhood, where we cracked down on free play from the 1980s, the milk cartons, the abducted children, all that stuff. We don’t let our kids out. So we reduce what they need, which is free play with each other, from the ’80s through about 2010, and then we bring in the phone-based childhood, the great rewiring.”