A talk by Charles A. Czeisler, MD, PhD, FRCP, Baldino Professor of Sleep Medicine and director, Division of Sleep Medicine, Harvard Medical School; chief, Division of Sleep Medicine, Brigham and Women’s Hospital. Moderated by Freda C. Lewis-Hall, MD, DFAPA, executive vice president and chief medical officer, Pfizer, and member of the HMS Board of Fellows. Harvard Medical School MED-EDs are a series of short, thought-provoking presentations by renowned HMS faculty, alumni, and leadership volunteers built to share and inspire new ideas.