Somewhat related (though not directly related to your problem): Flux ( http://www.stereopsis.com/flux/ http://www.stereopsis.com/flux/ ) It changes the color t

Somewhat related (though not directly related to your problem): Flux ( http://www.stereopsis.com/flux/ http://www.stereopsis.com/flux/ ) It changes the color temperature of your display. By reducing the amount of blue in the evening, the idea is that you can fall asleep easier and not tire your eyes out late at night. It's done purely by timezone/time of day (no sensors taken into account), but it works well enough for me. I don't know if I fall asleep any faster, but my eyes are certainly happier when browsing late at night. Note: The windows version is far more customizable than the mac version. I also haven't tried the linux one.