I am one of the people who love the idea of f.lux. I use it and it makes my eyes feel a lot better and makes me feel sleepy at the right times.<p>But the app itself is terribly broken, at least on El Capitan.  Whenever I switch modes, the screen flashes the original blue colors---my impression is that even a few seconds of blue light can mess up melatonin production, so this is unacceptable, especially from an app that is pushing the idea of color temperature mattering. Also, &quot;movie mode&quot; results in pulses of blue light every few seconds. Sometimes I select &quot;disable for an hour&quot; and nothing is disabled. &quot;Disable for current app&quot; is also spotty.<p>For this concept to work, and if the ideas about the effects of color temperature are true, then the implementation has to be completely solid. So I&#x27;m glad that Apple is duplicating the functionality of f.lux rather than supporting f.lux itself on iOS. I&#x27;ve also been looking into alternatives on OSX.<p>It&#x27;s time that we move on to an implementation that actually works.