Efficiency was defined as total sleep time (TST) over time in bed (lights off to lights on for PSG, and recording time for home tests). Wake after sleep ons...

https://www.apple.com/jp/healthcare/docs/site/Estimating_Sleep_Stages_from_Apple_Watch_Sept_2023.pdf

other trademark owned or licensed by Apple or any variations of such marks, including use of a genuine apple, for commercial purposes or register a trademar...

https://www.apple.com/jp/usergroups/registration/pdfs/UserGroupsSTL2003.pdf