Detailed description of the Problem:
Ticking the “Heart rate monitoring” option causes the HR sensor to be on and monitoring all the time until sleep tracking is manually switched off. This might actually be intended behaviour, however, this behaviour causes excessive battery drain and might actually reduce the lifetime of the green HR monitoring LED’s used by the watch. Heart rate should be monitored in intervals instead, thus falling in line with other HR monitoring apps (such as Google Fit and Cardiogram) and reducing battery strain.
Steps to reproduce:
Tick the “Heart rate monitoring” tick box found under “Settings”->“Wearables”->Heart rate monitoring" while having a Fossil Gen 5 Carlyle (FTW4025) actively connected (might apply to other WearOS devices as well).
Version of Sleep as Android:
v. 20200505