Some people think it's easier to fall asleep to a slowly decreasing light. This app will first set your screen to bright yellow, and then slowly make the screen darker and darker for about 15-20 minutes until the app closes and the screen is turned off. (If your device supports automatically turning off the screen.)
Place your phone close to your bed. You should see its screen shining up into the ceiling, but not look directly at the screen. This app offers no settings.