It's becoming common knowledge that exposure to blue light can suppress the production of melatonin, preventing your body from winding down properly before bed and making it more difficult to sleep, especially for those who remain on their devices throughout the evening. If you often work at night or simply like to read on a screen before going to sleep, this can be a game-changer.

Windows 10:

Windows can enable the "Night light" feature found in Settings > System > Display, which will automatically apply a similar filter to your display as the sun sets and then remove it at the sun rises.

Along with the ability to set custom hours, you can tweak the temperature of the filter with a manual slider in "Night light settings" and the feature can be enabled/disabled without returning to the settings by using the button in the Action Center (beside the Windows clock).  

MAC OS:

MAC OS users from Sierra 10.12.4 onward have an option called "Night Shift" which can be found by navigating to System Preferences > Displays > Night Shift (tab) and provides about the same level of functionality as already described for Windows 10.

Night Shift is also available on select iOS devices (iPhone 5s onward, iPod Touch 6G, iPad Air and newer, iPad Mini 2 and newer, and iPad Pro), head to Settings > Display & Brightness > Night Shift.