How does a smart watch track sleep?

1. Firstly, the built-in sensor is used to detect the state of sleeping, shallow sleeping or not sleeping, because it can detect the effect of heart rate, wrist motion frequency and amplitude. When wrist motion frequency is fast, amplitude is large and heart rate is high, it means that people sleep shallowly; When the wrist movement is very small and slight, and the heart rate is low, it is sleeping soundly.
2. Secondly, the sensor will measure heart rate and exercise parameters every two minutes. If the results of the previous measurement are similar to those of the current measurement, it means that it is always the same sleep mode, Then, after accumulation, it is the time of different stages such as deep sleep and shallow sleep, that is, the sleep time of each stage we finally saw. Note that the sensor does not work all the time, and the time of deep sleep is accumulated, which may not be continuous all the time, but may be segmented.
3. Finally, using the system algorithm in the watch, AI technology and the quality of sleep in big data gap, we make a comprehensive judgment, and then put forward some opinions on the possible problems in sleep, which is the working principle of smart watch to detect sleep.

Is the smart watch accurate in detecting sleep
The accuracy is very high, but not 100%, because there will always be errors in sensors and algorithms, and it is impossible to guarantee that they are always accurate. However, basically, the sleep time and state measured by the watch are still referential, so its sleep detection is generally accurate.

Do smart watches need to always turn on Bluetooth to detect sleep
Need. If you want to make the detection result more accurate, you should turn on Bluetooth and wear it on your wrist all the time, otherwise the detected data cannot be uploaded in real time, and the judgment of sleep quality may be deviated. In fact, when using smart watches, Bluetooth function usually needs to be turned on all the time.