Night Shift is a built in software feature of iOS and macOS. It was introduced in 2016-2017 into iOS in iOS 9.3 and into macOS in macOS Sierra 10.12.4.[1] The feature changes the color temperature of the display towards the warmer part of the color spectrum[2] that reduces some of the blue light from the screen.[3] Apple claims that the feature may help users have a better night's sleep by filtering blue wavelengths from the display, which suppress melatonin biosynthesis.[4] The feature is similar to the functionality f.lux provides.[5][6]