How do I get my BT Smart heart rate device work with Sleep as Android?

Please make sure you did enable Settings > Wearables > [Heart rate monitoring] Bluetooth Smart. Also try to pair with your device (this may not be required for all devices and OS versions). Make sure no other app is using your device while sleep tracking. If nothing helps please send us a debug report using [MENU] > Report a bug.

CAUTION: BT Smart heart rate tracking only works from Android 4.3 onward