1. Department of Physical Therapy, Graduate School of Health Sciences, Akita University: 1-1-1 Hondo, Akita, Akita 010-8543, Japan
2. International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Japan
3. Seiwa Hospital, Japan
4. Nikoniko-en Long-Term Care Health Facility, Japan
5. Sleep & Circadian Neurobiology Laboratory, Stanford Sleep Research Center, Stanford University School of Medicine, USA