abstract fun observeRemEpisodes(daysBack: Int): Flowable<List<RemEpisode>>
Returns Flowable that emits list of episodes of rem sleep for day
daysBack ago sorted ascending by time.
Data before specified day could be returned if they fall into sleep started before midnight. See Sleep for more information.
Episodes of rem sleep always fall into sleep episodes (e.g. there will not be any episode of rem sleep outside of a sleep episode and there will be no episodes of rem sleep at all if there are no sleep episodes).
Flowable that emits list of episodes of rem sleep for night
for how many days ago in relation to today information is needed.