If you have an iPad 10 this is the one.
Turns your screen bright white, (or colors) with no ads on the light itself. You can lock the color in if you find the perfect soothing shade for you. Purple for me. Also has strobe capabilities and an SOS setting on the left of the screen, and brightness on the right when you tap the screen, as well as a battery indicator for the iPad in the center. Excellent app that does what it says it does.