Your Philips health band automatically tracks time asleep and sleep stages (light, deep and REM sleep).

If you want to measure sleep efficiency, then you need to activate sleep mode manually by double tapping firmly and quickly the screen in that menu. Do this when you switch off the lights to go to sleep.

The health band automatically detects the moment when you actually fall asleep. Double tap the screen when you get up in the morning to deactivate sleep mode.

If you wake up in the middle of the night, you do not have to turn off sleep mode. The health band will automatically account for this wake period when calculating your sleep parameters.