F.lux will adjust your iPhone or iPad display to appear like sunlight during the day, and warm during nighttime hours to avoid looking at a bright screen. The app has settings to adjust the brightness level during the day and night, and you can also configure a time that you normally wake up each day.
Apple does not allow developers to access the Private APIs that f.lux requires to work on iOS, so the app is unlikely to appear on the App Store unless that policy changes. Since the app is side-loaded, there are no automatic updates, so the beta performs a daily update check and will display a message if a new version is available.
How to Sideload F.lux on iPhone and iPad
F.lux has provided step-by-step instructions on how to sideload the app on iPhone or iPad.