1 Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: michael.chee@nus.edu.sg.
2 Graduate School of Health Innovation, Kanagawa University of Human Services, Kawasaki, Japan; Precision Health, Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Japan; Department of Clinical Sciences, Lund University, Skåne University Hospital, Malmö, Sweden.