What does applewatch think of deep sleep?

Smart wearable devices can monitor sports health, such as heart rate monitoring, blood oxygen monitoring, sleep monitoring and so on. Applewatch can also support sleep monitoring, so what does apple watch think about deep sleep?

What does applewatch think of deep sleep? 1. Open the sleep APP of Apple Watch or the health app of mobile phone, and set the sleep goal.

2. Wear a watch to sleep, Apple? Watches can track deep sleep, that is, sleep time. Open the "Sleep" App after getting up, find out how long you have slept, and check your sleep trend in the past 14 days.

This paper takes Apple Watch Series 6 as an example and applies it to WatchOS 7 system.