First, make sure you have the latest version of Pillow, iOS, and watchOS.
Ensure Pillow has proper access to Motion & Fitness data:
1) Restart your iPhone and Apple Watch
2) Make sure the iPhone and Apple are connected to each other and in range.
3) Open the Settings app on your iPhone
4) Tap the "Privacy" menu and select "Motion & Fitness."
5) Flip off and then back on the switch that corresponds to Pillow
6) Attempt to open the sleep statistics on Pillow on the Apple Watch.
Add Pillow's complication on a watch face.
If you don't have any space in the watch faces you currently use, please add a new one and add Pillow's complication there.
Keep Pillow in Dock:
Open Pillow on the Apple Watch > Press the button on the side of the Apple Watch to bring up the Dock > Tap "Keep in dock."
Keep the Apple Watch on your wrist until sleep analysis has completed
When you stop a session in the morning, Pillow will need some time to analyze your data and will display a progress bar of this process. Please keep your Apple Watch on your wrist until the progress bar has reached 100%.
Setup the iPhone to automatically set the time and date.
This should be the default setting. However, if you have selected to set up the time and date manually, there could be several issues with sleep analysis. To set time and date automatically:
Open the Settings app on your iPhone > Go to: General > Date & Time > Turn on: "Set Automatically".
Set the Apple Watch to Wake the Screen with 1 hour.
On your Apple Watch: Open the "Settings" app > Wake Screen > Turn On: "Wake Screen on Wrist Raise" and right after that "On screen raise show last app": "Within 1 Hour of Last Use".
The above setting will ensure that Pillow remains in focus as long as needed
Failed analysis due to an update of iOS or watchOS version.
In some rare cases, analysis can fail if iOS or watchOS upgrade during the night that the session was running. In those cases, sleep analysis data for that night might not be recoverable.
If analysis continues to fail despite having verified the above, we would recommend as a last resort to attempt unpairing and re-paring your Apple Watch to the iPhone.
Via web: https://pillow.uservoice.com
From your iPhone: Open Pillow on the iPhone > Tap on the settings icon > Select 'Helpdesk'