This article discusses common troubleshooting steps regarding various problems that might occur while synchronizing sleep data using iCloud:
Recommended steps:
Make sure you have enabled iCloud syncing in Pillow:
Open Pillow on your iPhone/iPad. > Tap on the "Settings" icon in the top right corner. > Scroll down and make sure "Sync with iCloud" is turned ON.Check the Apple System Status page to make sure there are no outages or scheduled maintenances currently affecting iCloud.
Update your computer or device to the latest software version. See iCloud system requirements for more information.
Ensure that you are logged in to iCloud with the same Apple ID on all your iOS devices: Open the "Settings" app > [your name] > iCloud.
Note: If you use the same Apple ID for iCloud as you do for other Apple services, (for example, Apple Online Store, iTunes Store, or Mac App Store), changing your Apple ID password also changes your password for the other Apple services.