If you have not made any recent changes to your devices or settings and SleepWatch abruptly stops working you might need to reset your permissions.
Sometimes after a software update, these can get out of sync and need to be reset even though it may look like they are correct
To reset your Health app permissions complete the following steps:
1. Open the "settings" (it looks like a gear) on your iPhone
2. In settings, select the "Apple Health" app on your iPhone (It has a white icon with a red heart)
3. Choose "Data Access & Devices"
4. Select SleepWatch
5. Turn OFF all the available switches
6. Restart your iPhone
7. re-open the “Apple Health app” in settings on your iPhone > Tap on the “Sources” tab > Select “Sleep Watch” > Turn ON all switches
After that (VERY IMPORTANT) Restart your Apple Watch
If you need additional assistance please use the "feedback and support" option under the "account" tab in SleepWatch app.