The iPad is a great way to enjoy a book in bed before going to sleep, but staring at a bright screen is not the best way to ensure a good night's sleep. This is why Apple has introduced Night Shift mode in iOS 9.3. Night Shift mode is available on both iPad Air models, both iPad Pro models and the iPad mini 2-4. You can enable Night Shift mode on the Display & Brightness section of your Settings app.
You can choose to have Night Shift automatically turn on and off at a selected time or manually enable it when you want to use it in the Settings.
Night Shift adjusts the colors of your iOS device's display to make reading or using your device easier on the eyes at nighttime.