It is no secret that Apple is constantly thinking about how to expand the functionality of its smart watch. This is indicated by the numerous patent applications and some network sources. For example, recently Bloomberg became aware of the fact that the cupertinos have for several months testing the function of tracking sleep in the Apple Watch.
In the first versions of its smartwatch, the cupertinos have deliberately refused to implement the sleep tracking. It was assumed that this was due to the low autonomy of the Apple Watch. However, a large number of sleep trackers, which have recently created third-party developers forced Apple to reconsider its opinion. In the end, sources familiar with the plans of Apple, reported that the sleep tracker can appear in the Apple Watch in 2020.
Most likely, along with a new feature Apple will try to increase the autonomy of its smart watch. It is possible that the Apple Watch will be a special energy saving mode which can be activated at night.