F.lux is a tiny piece of software that adjusts the color of a computer display to the time of day, warm at night and like sunlight during the day.
After installing f.lux which is a piece of cake, you have enter your location. The software adjusts the color and brightness of the monitor according to these daylight settings and actual time.
It took me little time to get used to the new display settings. It's less bright at night and a bit 'warmer'. Since I experienced it's less tiring for my eyes, I won't live without it. Nor at work, nor at home. F.lux consumes on my (desktop) computer about 5 MB of RAM.