You shouldn't be looking at your phone just before bed. It could be ruining your sleep if you! The latest iOS update will be able to help you sleep better by reducing the blue light emitted from the screens.
Called "Night Shift" it will reduce the iPhone's blue light when it gets dark.
You'll need to update to iOS 9.3. You can also set it in Settings > Display & Brightness > Night Shift
The iPhone will automatically enable Night Shift based on sunset/sunrise times in your location.
And it'll work like this:
Great! Good sleep from now on then!