Have you updated to iOS 9.3 yet? The reason I ask is because it contains a cool new feature called Night Shift.
At sunset, Night Shift will change the color of your display to a warmer hue and then back to normal in the morning. This shift from looking at a screen with a bright blue tint to one with a warmer, yellowish tint, is supposed to make it easier to fall asleep at night.
(I find myself turning it on in the daytime sometimes as well – I personally find it to be easier on my migraine-prone eyeballs).
Give it a try. You can turn it on in Settings – Display and Brightness – Night Shift
If you leave the “Scheduled” switch off, it will automatically change whenever your phone determines that it’s sunset in your area. If you’d rather schedule it for a specific time frame, just turn the switch on and choose the time frame.
You also have the choice to “Manually enable until tomorrow” and it will ignore your schedule and just stay on until the next day.
Down at the bottom, you can adjust how warm you want the screen to be with the slider.
(Night Shift is available on iPhone 5s or later, iPad Pro, iPad Air or later, iPad mini 2 or later, and iPod touch-6th generation.)
And of course, you can pair Night Shift with the super-awesome and free white noise app, NiteFan, for the best night sleep ever. NiteFan simulates the sound of a fan and allows you to mix and match sounds until you find the perfect one. Developed by yours truly.