I request you to please guide us on how Samsung Health calculates and shows sleep and SleepStages data in Samsung health app.?
If you go watch the [Samsung UnPacked 2023 YouTube replay(Samsung Galaxy Unpacked July 2023: Official Replay - YouTube) when they announce the new Watch 6 they do go into detail on how this is done.
It is about 45 mins into the unpacked so you may want to fast forward a bit.
Samsung Developer Relations