How does Apple monitor sleep quality?

Apple phones monitor sleep quality through health applications.

The sleep monitoring function of Apple mobile phone is integrated into health applications. Users only need to open the health application, click the "Browse" option, and then select "Sleep" to view the sleep status. This function provides a statistical summary of sleep conditions in a day or longer, including total sleep time, sleep cycle, sleep quality and other information. These data help users to understand their sleep patterns and habits, thus improving the quality of sleep.