I have the same problem. Often I have 30ish mind of deep sleep directly after sync. But later when I check my sleep data for the same night it is often much less like 4 mins or even —.
same problem, and no idea why it is doing this. :-(
Seeing the same problem. - Right after the sync the sleep stats are "believable", just to change significantly some time later (30-120 min). E.g. from 50 min deep sleep to 4 minutes or none at all.…
found this on the sleep support page:
Sleep windows may recalculate throughout the day to verify and distinguish between waking up early and going back to sleep vs being up for the entire day. You may notice slight variances in your complete sleep window as these calculations update. Even with these recalculations, sleep monitoring can still stop if the device detects movement that indicates you've entered an "awake" state for an extended period of time during the night.