The Apple Watch does not yet offer a sleep tracking feature as part of first party software (there are third party apps available though). This is partly down to Apple’s tardiness on introducing it but also the fact that most Apple Watches only last waking hours on a single charge and so need to be charged overnight.
You’ll obviously need to wear your Watch to bed to be able to use the sleep tracking feature, which is known as “Time in Bed tracking” internally at Apple.
The report claims the mode will introduce a feature that reminds wearers to charge their Apple Watch before they go to bed in order to get around this problem of short battery life. The Watch will track sleep with movement, heart rate, and noise using the microphones – more variables than rivals like Fitbit can offer.
If the feature is announced on 10 September alongside the expected new iPhones, it could be as part of an Apple Watch Series 5 launch, or perhaps an addition to the existing Series 4 to keep current users happy and attract more buyers as we come into the holidays.