Sleep as Android can detect your REM Phases and provides this feature. It even supports smart watches😀
https://play.google.com/store/apps/details?id=com.urbandroid.sleep
Sleep as Android can detect your REM Phases and provides this feature. It even supports smart watches😀
https://play.google.com/store/apps/details?id=com.urbandroid.sleep
Is this even worth a news in the USA?