1. Department of Psychiatric and Mental Health Nursing, Graduate School of Nursing Science; St. Luke's International University; Tokyo Japan
2. Department of Neuropsychiatry; Kyorin University School of Medicine; Tokyo Japan
3. Department of Epidemiology and Biostatistics for Nursing, Graduate School of Nursing Science; St. Luke's International University; Tokyo Japan
4. Department of Sleep-Wake Disorders, National Institute of Mental Health; National Center of Neurology and Psychiatry; Tokyo Japan
5. Department of Psychiatry; The Jikei University School of Medicine; Tokyo Japan
6. Division of Population Medicine; Cardiff University; Cardiff UK
7. Department of Public Health, Faculty of Health Science; University of Stavanger; Stavanger Norway
8. Faculty of Health Sciences and Social Care; Molde University College; Molde Norway
9. Department of Neuropsychiatry; University of the Ryukyus; Okinawa Japan
10. Department of Psychiatry; Soseikai General Hospital; Kyoto Japan
11. Nursing, Midwifery and Allied Health Professions Research Unit; The University of Stirling; Scotland UK