F.lux - an eye saver program

It saves your eyes from unusually bright and florescent screens by adapting them according to time of day. I've been using it and I'm very impressed with what it does, makes me feel warm at night and fresh in the morning when looking at my PC. With this program running in background, you would love the way your computer screen changes with time.

(Extract from their website)
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.

It's available for Windows,Mac,Linux and iOS.
You can download from here