1. University of Pennsylvania School of Nursing, Philadelphia, Pennsylvania
2. Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
3. Division of Sleep Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
4. Department of Medicine, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, Pennsylvania
5. Institute of Human Genomic Study, Korea University Ansan Hospital, Ansan, Korea
6. School of Medicine, Korea University, Seoul, Korea