I believe the fenix 8 is lagging behind in terms of sleep measurement and they should fix it, the program is completely useless... today for example I slept 3 hours at night and another one at noon that it never recorded, it should be like the Huawei watches, which when you sleep no matter how much you sleep, it simply adds the time together every day and at 12 at night it resets to zero so that it can measure the new time again, as simple as that.
We should all write to Garmin together so they can fix it.