Also, I&#x27;ve looked at f.lux&#x27;d screens set to the reddest possible setting through a 470nm narrow band filter. There&#x27;s still light at the worst color band which gets through. If you are exposing yourself to light over an extended period of time, it doesn&#x27;t take much to suppress melatonin secretion. (One study found suppression at levels low as 0.5 lumen or lux -- one of those two. Either way it&#x27;s not much. About commensurate with the light from a brightly lit hall coming in through the gap under your door.)