Where is this battery draining code from?

I uninstalled 'Sleep Log' the other day and so far the battery seem to drop ca 10 % per day - back within reasonable bounds I say. If that continues I will be satisfied.

I am under the impression Sleep Log mostly looks at data that the watch provides already, regarding movement, and so shouldn't cause sensors to be used more often then they would otherwise. But I guess the app does many writes to the storage, so that could be what's caused the increased battery consumption?

Have anyone else noticed if Sleep Log very noticably impacts battery use?