This app lets you check for correlations between your mood and sleep/exercise patterns.

You will be prompted to allow access of your sleeping and walking data from Health app. If you are not using Health app to track that data or you don't want to allow access, you can always enter those numbers manually for each date.

Every evening application will ask you how would you rate your day. (You can opt-in for push notifications. In that case it's easier, so that you would not forget making that entry)

All the data that app gathered will be presented in chart. So you can check if your sleeping time or walking patterns correlate with your mood.