Stop Blue Light at Bedtime
Many people are aware that the blue light from screens can negatively affect sleep. Fortunately, most devices allow for a blue light filter, which minimizes this light close to bedtime to promote better sleep.
iOS
iOS has a feature called Night Shift, which allows you to set a specific range of time during which blue light from the device is minimized. This can be found in Settings > Display & Brightness > Night Shift. There, you can set a schedule, manually enable until the next day, and adjust the temperature to find the best screen warmth for you. This works on iOS 9.3 or higher.
Android
Android does not come with a specific program for reducing blue light, but there are a couple of third-party apps that will do the job. Search for Blue Light Filter, sFilter, or Twilight on the Google Play Store. All three apps allow you to schedule when to enable the blue light filter and adjust the warmth, so it’s a matter of personal preference.
Windows
PCs that have Windows 10 installed include a feature called Night Light. This can be reached by going to Start button > Settings > System. Toggle on the switch for Night Light, then click Night light settings. Within this setting, you can turn on Night Light immediately or set a scheduled range of time during which to enable Night Light. You can also use the slider to adjust the warmth.
MacOS
On MacOS Sierra 10.12.4 and later systems, go to the Apple menu > System Preferences > Displays. Select the Night Shift tab. You can schedule when you want Night Shift to be enacted or enable it at that moment. You can also use the slider to select your desired screen temperature. Night Shift can also be turned on and off from the Notifications Center.
Adapted from http://www.pcmag.com/news/354971/how-to-stop-gadget-blue-light-from-disturbing-your-sleep and http://support.apple.com/en-us/HT207513.