*This is not my software and I am not affiliated with f.lux software by any means*
This is free software for Windows, Linux, Mac and iPhones/iPads.
What it does, it calibrates your screen colors' temperature according to time of the day in your geographical region.
You can find dozens of articles saying that the blue glow from screens at the night is a signal for brain that "it's daytime" and it should stay active and ready. That way you get sleep malfunction.
Enough of BS I installed it 3 days ago and it's a keeper.