Non-24 Hour Disorder (Non-24) is a circadian rhythm disorder affecting the majority of people with no light perception. It results in cycles of difficulty sleeping at night and strong desire for sleep during the day. Join Seminars@Hadley as Dewey McLinn III, PhD, director of Medical Science Liaisons at Vanda Pharmaceuticals, reviews the aspects of Non-24, and discusses the disorder with a person living with this condition.