1. Department of Physical Therapy Akita University Graduate School of Health Sciences Akita Japan
2. Department of Psychiatry Akita University Graduate School of Medicine Akita Japan
3. International Institute for Integrative Sleep Medicine (WPI‐IIIS) University of Tsukuba Tsukuba Japan
4. Nikoniko‐en, Long‐Term Care Health Facilities Akita Japan
5. Ibaraki Prefectural Medical Center of Psychiatry Kasama Japan
6. Sleep & Circadian Neurobiology Laboratory, Stanford Sleep Research Center Stanford University School of Medicine Palo Alto California USA