STERN BUSINESS Magazine | From Research to Revolution

You describe a “Great Rewiring” of childhood: a shift from play-based to phone-based lives. What is the psychological impact of this shift, and why does it show up so starkly in the data on teen mental health?

In The Anxious Generation we coined the term “The Great Rewiring” to describe the period from 2010 to 2015 when kids’ social lives moved largely online (upwards of 7-9 hours a day) and away from in-person social interaction with friends, family, and their local community. During this period, the “play-based childhood” was replaced by the “phone-based childhood.” This Great Rewiring of childhood interferes with children’s social and psychological development, covering everything from sleep deprivation to attention fragmentation, addiction, loneliness, social contagion, social comparison, and perfectionism.

Photo: Haidt with Oprah Winfrey on her podcast

To understand the impact of this Great Rewiring on teen mental health, we must first look at what is happening to the brain during that time of life (i.e. puberty). Developmental psychologists see puberty as a “sensitive period” in which the brain is especially “plastic” or malleable based on incoming experience. The brain is changing over from the child form to the adult form, and those changes are guided by whatever a child does repeatedly. Neurons that fire together wire together, as brain researchers say.

The average adolescent in the US now spends around five hours a day using social media. Their brains will enhance whichever neurons and circuits are activated repeatedly, at the expense of neurons and circuits that are underused. This brain sculpting happens throughout childhood, and continues on in the pre-frontal cortex until around age 25. But in the earlier part of adolescence—specifically puberty—the sculpting is more intense, and the changes are more likely to be permanent.

So what has the result been since the social lives of American teens moved largely onto smartphones loaded with social media apps between 2010 and 2015? The adolescent mental health crisis. Major depressive episodes among American teens have more than doubled since 2010. Emergency department visits for self-harm episodes among preteen girls have more than tripled. Suicide rates have also risen significantly.

Photo: Haidt with Meutya Hafid

What role do technology and social media companies play in this?

Big Tech and the social media companies hold a great deal of responsibility for what has happened to our kids. Recent research—including experiments conducted by Meta itself—provides increasingly strong causal evidence linking heavy social media use to depression, anxiety, and other internalizing disorders.

Importantly, in March 2026 we reached a new frontier in the fight for accountability. Juries in Los Angeles and New Mexico affirmed what parents have long known: Meta and YouTube were designed to exploit young people, with devastating consequences.

For the first time, the law aligns with common sense: social media companies no longer have a special exemption to harm children with impunity. Their shield is gone. They will be treated like any industry that knowingly harms children and lies about it. History will judge them as harshly as the tobacco industry.

This movement has found a broad and diverse coalition of support, ranging from grassroots parenting organizations to international heads of state. Has there been an unexpected moment from your conversations with these groups that you can share?

One of the most moving moments I’ve experienced since publishing The Anxious Generation came in early 2026. I was in London and was invited to meet with Keir Starmer’s policy team at #10 Downing. On my way out, right as I reached the gate, I ran into a dozen survivor parents who were there to lobby the government to enact protections, so that there would be fewer parents, like themselves, who would know the pain of losing a child to the dangers of social media. I had heard a few of their stories already and was immediately overwhelmed by emotion. I got so choked up I literally could not speak. Instead, we stood together and hugged.

What have you heard from students taking your popular courses Work, Wisdom and Happiness, and Flourishing about the impact of phone and social media use in their lives, and advice to curb it?

In these classes, I ask students to change a few of their habits to make themselves smarter, stronger, and more sociable. To begin, I strongly urge those who are spending more than two hours a day on social media to work on cutting that time down. Those who are able to reduce their usage always drastically get transformative results, without fail. When they aren’t spending so much time stuck in an infinite scroll, they have so much more focus that they can finish their homework quickly and then find that they have an extra three or four hours in each day. They are less stressed. They start spending more time with friends. They flourish.

Photo: Haidt with Emmanuel Macron at the 2026 World Economic Forum

We now have AI as another looming threat facing children, and the idea that chat bots and virtual friends may replace real life relationships. How do we begin to address this next challenge?

Just as smartphones and social media replaced childhood play and in-person peer interaction, AI companions threaten to exacerbate and extend these risks as they simulate friendship, affection, and understanding, and offer “comfort without commitment,” a form of intimacy without vulnerability.

If we want children to grow into socially, emotionally, and morally capable adults, we must protect childhood as a space for real human connection. My plea to parents is this: until AI is proven safe, please keep AI chatbots companions out of childhood.

One of your central themes to returning to a phone-free childhood is “collective action.” For Stern alumni who are leaders and parents or have children in their lives, what is the single most effective way they can contribute to this movement within their own communities?

The tide is turning on this issue. Before, we had a perception of reality before that this was just inevitable: “What are you going to do? The kids are on it. The technology is here to stay.” Today we’re asking: “If everybody agrees this is harmful for kids, why are we giving it to kids?”

This work is all about collective action. No parent wants to be the only one who doesn’t let their kid have a smartphone or social media—but when we act together, the benefits multiply and the risks of going it alone disappear.

Jonathan Haidt’s bestselling book The Anxious Generation sparked a global conversation that grew into a movement.