T is counter intuitive, but the reason that the hone dims in low light and brightens in higher light is that instead of the surrounding light lighting up your screens display(like one would think), the screen of your phone actually reflects the light causing it to act like a mirror and sending the surrounding light back at you. To compensate for this increase of light being sent at you, your phone will make the display brighter. in low light settings, it doesn’t need to be as bright via the same logic. Also in low light areas our eyes become accustomed to the low light and bright light tends to irritate our eyes. this is the other reason it is dimmed in low light settings.