Is there a bracelet or smartwatch for tracking sleep time that is not tied to the cycle of day and night?

Question

Time Management

For example, the mode of operation is a day after two.
Or, for example, a person took a nap during the day for 2 hours. Or like Stirlitz, exactly 20 minutes.
As a last resort, there should be a button that can be used to forcibly inform about the beginning of sleep (a button on the device itself or in an application in a connected smartphone, it doesn’t matter).

Answer 1

Huawei Honor Band 4, only 20 minutes it does not track, most likely, from 2 hours sleep is considered, if my memory serves me right