Funding for this research was provided by:
National Medical Research Council Singapore (STAR19may-0001)
Received: 15 March 2021
Accepted: 1 July 2021
First Online: 13 July 2021
Competing of interest
: M.K. and H.K. are employees of Oura Health, but this work represents their individual opinion and initiative. The other authors declare no competing interests.