1. Department of Neuropsychiatry, Graduate School of Medicine University of the Ryukyus Okinawa Japan
2. Department of Psychiatry Nihon University School of Medicine Tokyo Japan
3. Eisai Inc. Nutley New Jersey USA
4. Eisai Ltd. Hatfield UK
5. Eisai Co., Ltd. Tokyo Japan
6. Department of Sleep‐Wake Disorders, National Institute of Mental Health National Center of Neurology and Psychiatry Tokyo Japan