Add go to sleep mood
I can state how I feel when I wake up, please add the same for going to sleep. This is to see how often I go to sleep feeling happy or unhappy and then I should be able to see the effect my mood has on the quality of my sleep.
This functionality can be replicated by using Notes. For each mood (Good, Bad etc.) add a single note and select the note corresponding to the mood at the start of each sleep session. You can view how each note affects your sleep quality in the detailed statistics view by rotating your device horizontally.