Summon Quick Settings by pressing the button under the right touchpad and tap the cogwheel icon on the slide-out menu. You can manually adjust brightness by moving the slider back and forth ...

This is also known as the Reduce Blue Light setting, and can be found by pressing the Settings cogwheel in the top corner, going to Picture, down to Advanced Settings, and then down to Reduce Blue ...

Prior to Android 5.0 Lollipop, you could access it by swiping down from the top of your device's screen to reveal the notification shade, then tap on a Settings icon. You could also jump straight ...