Funding for this research was provided by:
Japan Society for the Promotion of Science (JP17K17534)
Received: 31 October 2019
Accepted: 9 March 2020
First Online: 20 March 2020
Ethics approval and consent to participate
: Ethical approval for this survey was granted by the Ethical Committee of the Tokyo Medical University and Institute of Neuropsychiatry. All participants completed a written informed consent.
: Not applicable.
: Department of Somnology is an endowment department, supported with an unrestricted grant from Philips Japan Co., Ltd. and Koike Medical Co., Ltd.