I think the app would benefit a lot from more user fine tunning in motion detection and awake detection. For example, my resting heart rate is quite low and stable (especially during sleep), so even on the “low” sensitivity it takes only ~12 bpm increase to mark that period as awake, while in reality I am still sound asleep.
An overlapping comment: The tuning could be done automatically based on observed resting heart rate, for instance by using a minimum increase to count as awake, or (better?) computing the point to point variance and looking for things that exceed that by one or two σ to count as awake.
I have the same experience as SafteyOwl with low RHR causing problems.