Adolescents in the U.S. are severely distressed, increasingly suicidal. Zach Rausch and Jonathan Haidt weigh in on causation: “The sudden switch from play-based childhood to phone-based childhood is—we believe—the leading candidate for being the major cause of the international collapse of adolescent mental health.8 The evidence of causation is particularly strong for girls. In fact, nobody has yet put forth an alternative theory—one that can explain why the same thing happened at the same time in so many countries. Jean Twenge recently considered thirteen such theories that have been proposed to explain trends in the U.S., and she showed that they don’t even work in the U.S., let alone internationally.”