f.Lux is a cool little utility that appeals to the lighting geek in me. What it does is adjusts the color temperature of your monitor or laptop screen, based on the time of day, "warming it up" at night and "cooling down" during the daytime, because it has been shown that looking at cool illuminants in the evening can screw up your circadian rhythm.
This is no joke; when your circadian entrainment is screwed up, it's been linked to all kinds of problems such as depression, several types of cancer, diabetes, heart disease, and obesity. Matter of fact, night shift work -- which generally involves people being wide awake and working, generally under cool fluorescent light -- is so damaging to our cicradian entrainment that it's been classified as a Class 2A carcinogen by the World Health Organization. Ain't that some shit?
This brings me back to f.Lux. I played with this as an iOS app a while back on an old jailbroken iPhone4, but just discovered that it's available for Mac OS 10.9, and I recently loaded it up on my lappie. It's awesome. From the docs:
f.lux makes your computer screen look like the room you're in, all the time. When the sun sets, it makes your computer look like your indoor lights. In the morning, it makes things look like sunlight again.
Tell f.lux what kind of lighting you have, and where you live. Then forget about it. f.lux will do the rest, automatically.