They record not only large movements that would be visible to the naked eye but also more subtle movements, including those generated from breathing. This t...

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

and iPad is a secure home for health data and trends (Apple Inc. 2023), including Headphone Audio Levels, Environmental Sound Levels (from the Noise app on ...

https://www.apple.com/jp/health/pdf/Hearing_Health_Features_on_AirPods_Pro_2_October_2024.pdf