It’s hard to believe sometimes that smartphones and social media haven’t been around forever — but for one generation, they have. Gen Z doesn’t know a time when they weren’t ubiquitous. This cohort also happens to be the generation with the worst mental health in America. Is that a coincidence?

The social psychologist Jonathan Haidt has reams of data to argue it’s not. And in his new book, The Anxious Generation: How the Great Rewiring of Childhood Is Causing an Epidemic of Mental Illness, he is launching a shot in what he hopes will become a full-scale war against social media and smartphone use by kids and teens