The iPhone already supports various &#x27;filters&#x27; through its Accessibility settings. I use the &#x27;Low Light&#x27; filter every night, which allows the screen to go darker than usual. If they were to just add a low-light redshifted filter, that would be fine for most people I think.<p>However, and to f.lux&#x27;s point, people should expect their devices will keep their health in mind. I believe Apple is worried that opening up first class support for this sort of functionality is an admission that blue light is hazardous to one&#x27;s sleep health, which could open them up to various liabilities.