Night Mode" option to decrease blue light exposure
Similar to what applications like "f.lux" have been accomplishing on computers. Most modern computer operating systems (including Windows 10), Android phones, and iPhones now offer this feature natively.

Link to Apple article on it: https://support.apple.com/en-ca/HT207570

Excerpt: "Night Shift automatically adjusts the colors of your display to the warmer end of the spectrum—making the display easier on your eyes.

Night Shift uses the clock and geolocation of your iOS device to determine when it’s sunset in your location. Then it automatically shifts the colors of your display to warmer colors. In the morning, it returns the display to its regular settings."