First, please make sure that your app and watch firmware are on the latest version available.
After so, please do the following:
1.) Make sure to enable auto-sleep or have the preset bedtime and awake time.
2.) Ensure your device is On, has a full battery, and is connected to the app.
3.) To sync, go into your sleep screen and pull down to start the syncing process.
4.) Note that the Sleep Counter starts tracking when the watch is on Sleep mode and no longer sense any movement.
After doing the steps above, please do the Basic reset below:
-Unpair watch from your phone.
-Delete the Aviator App
-Press both the Upper and Lower pusher buttons of the watch together and hold for 3 seconds while watch is on the Charger.
-Re-install the App
-Pair the watch again.