Kudos to Geoffrey for telling me about F.lux.  This is a fantastic utility for those who work (or play:) on their computers into the wee hours.  Even better, have you awakened in the middle of the night to do some work on your computer, only to be blinded by the screen?!  Holy light from beyond and back — the glare is terrific!  

There are studies suggesting that, although blue light is beneficial during the day, late at night, blue light can negatively affect your sleep pattern.  My own experience suggests that F.lux not only makes it easier to work on your computer at night, but apparently my sleep pattern WAS being interrupted; I now find I am sleeping better and for longer than my normal 4-5 hours a night.  You can adjust the settings and, if you need to work on web design (exact colors, etc.), you can disable the utilty for an hour.  If you are simply writing code, the lighting will not affect your results.  This is a small-footprint application with a large payoff and I am so grateful Geoffrey told me about it.