MATT RICHTEL is a health and science reporter at the New York Times . He spent nearly two years reporting on the teenage mental-health crisis for the paper's acclaimed multipart series Inner Pandemic, which won first place in public-health reporting from the Awards for Excellence in Health Care Journalism and inspired his book How We Grow Up: Understanding Adolescence. He received the Pulitzer Prize for national reporting for a series of articles about distracted driving, which he expanded into his first nonfiction book, A Deadly Wandering , a New York Times bestseller. His second nonfiction book, An Elegant Defense , on the human immune system, was a national bestseller and chosen by Bill Gates for his annual Summer Reading List.