1. Department of Psychiatry, Korea University College of Medicine , Seoul, South Korea
2. Sleep-Wake Disorders Center, Korea University Anam Hospital , Seoul, South Korea
3. Department of Psychiatry, Gachon University School of Medicine , Incheon, South Korea
4. Department of Neurology, Seoul University College of Medicine , Seoul, South Korea
5. Department of Preventive Medicine, Korea University College of Medicine , Seoul, South Korea