Conflict of interest

S. Okumura reports personal fees from Philips outside the submitted work; stock of MaRI Co., Ltd. outside the submitted work. S. Sato reports grants from Philips Japan, Fukuda Denshi, Fukuda Lifetec Keiji, ResMed, and Nippon Boehringer Ingelheim outside the submitted work. T. Hirai reports grants from Philips Japan, Fukuda Denshi, Fukuda Lifetec Keiji, and ResMed outside the submitted work. T. Sakamoto reports royalties or licenses from Ohmsha Ltd. and MaRI Co., Ltd.; personal fees from GLORY LTD, Sumitomo Electric Industries Ltd, Mitsubishi Electric Corporation, Science & Technology Co., Ltd., Think&Act, Inc., KEYCOM Corporation, and others; patents pending from US Provisional Patent Application nos. 63275949 and 63299958 outside the submitted work. H. Taki reports grants from MaRI Co., Ltd.; personal fees from Kyoto University; stock and stock options of MaRI Co., Ltd. outside the submitted work. Y. Gon reports grants from Philips Japan, Fukuda Denshi, Fukuda Tokyo, and ResMed outside the submitted work. K. Chin reports grants from the Research Foundation for Healthy Aging during the conduct of the study; grants from Philips, Fukuda Denshi, Fukuda Lifetec Keiji and Tokyo, ResMed, and Eisai,; personal fees from Shionogi, Aculys Pharm, and Lilly Japan outside the submitted work. M. Hoshi, Y. Kozu, D. Endo, T. Ito, K. Nagata, H. Hiranuma, and T. Akahoshi report nothing to disclose.

Ethical approval

This study was approved by the Institutional Review Board of Nihon University School of Medicine (Approval No. 210914-5). All Procedures performed in studies involving human participants were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments.

Informed consent

Written informed consent was obtained from all individual participants included in the study.