NORMAN E. ROSENTHAL, M.D., is a clinical professor of psychiatry at Georgetown Medical School and the New York Times-bestselling author of books including Transcendence: Healing and Transformation Through Transcendental Meditation and The Gift of Adversity: The Unexpected Benefits of Life's Difficulties, Setbacks, and Imperfections. He conducted research at the National Institute of Mental Health as a research fellow, researcher, and senior researcher for more than twenty years and was the first psychiatrist to describe and diagnose Seasonal Affective Disorder (SAD).