If the nap time is too short, less than 20 minutes, or the body or wrist is violently moving during the nap, the bracelet will not record sleep data.
The reason why there are many sleep data records: In reading, watching videos, watching TV, sitting in an office and other scenes, the wrist movements are very similar to those when falling asleep, which may be judged as sleep, leading to an erroneous increase in sleep duration.
After you wake up, if you exercise less or don't operate the screen, the bracelet will not exit the sleep mode immediately, which may lead to an incorrect increase in sleep duration.