Why is there a red bar / section / block in my sleep graph?
The red block indicates that something went wrong with tracking at that time and the device stopped providing sensor data for some reason. Usually those are some non-standard battery optimizations or battery savers, the battery gets too low so we preserve it for the alarm or connectivity issue if you use a wearable.
1. Battery restrictions
Make sure no system restrictions are applied to Sleep, or any involved apps like wearable companion app).
See our guide here, and follow the instructions.
2. Too low battery
When the battery is too low (usually below 10%), data collecting is terminated to preserve enough battery for alarm.
When the battery was too low, there is a battery icon is displayed on the graph:
3. Connectivity issues with a wearable
When the connection with the wearable is lost, you can see red sections on the graph. The app always tries to reach the wearable again.
The graph can look like this:
Opt-out from any battery restrictions is applied by your system (https://dontkillmyapp.com/)
Pair the wearable with your phone in System settings.
Make sure the BT is not lost, and try lowering the distance between the phone and the wearable.
Try settings the device as Trusted device.
Tags: tracking, graph, huawei, samsung, oneplus, 1+, xiaomi, meizu, asus, wiko, lenovo, oppo, nokia, sony, pixel, nexus, htc