Sleep tracking apps on Android will soon use less power Android apps that have to run in the background like sleep-trackers have had a rough time. Among other things, they suffer inconsistent and unreliable background app limitations across different Android versions, which can interfere with how the apps work at a very fundamental level. This doesn't fix that issue, but today Google is rolling out a specific API just for those apps, letting them pull sleep duration data right from the system itself. The API is built into the existing Activity Recognition suite, which (if you allow it) can automatically pick up on the things you're doing based on the device sensors. That's how things like Google Fit can determine whether you're biking, walking, or driving when it comes to tracking physical activity. Google already uses the Sleep API internally for the Google Clock's bedtime mode.