The day after New Year's, John Reichert of Boulder, Colorado, had a heated argument with his 14-year-old son, James. "I've failed you as a father," he told the boy despairingly.

During the long months of lockdowns and shuttered schools, Reichert, like many parents, overlooked the vastly increasing time that his son was spending on video games and social media. Now, James, who used to focus his free time on mountain biking and playing basketball, devotes nearly all of his leisure hours – about 40 a week – to Xbox and his phone. During their argument, he pleaded with his father not to restrict access, calling his phone his "whole life".