Using Pillow with your iPhone or iPad
In order for Pillow sleep tracking to work properly, your device should be placed face down on your bed, in a position near your body (a distance of about 15-25cm should suffice). In case you're seeing more "awake" time than expected, you can also try moving your device a little bit further from your body. We would also recommend avoiding covering your device with heavy blankets and bed covers in order to avoid overheating of the device.
Using Pillow with your Apple Watch
To use Pillow with your Apple Watch, your Apple Watch must be on your wrist through the sleep session. In addition, if you want to use the Alarm and Sound recording feature your iPhone must be placed within arm's reach but NOT on your mattress. You can place it on the nightstand or a nearby surface.