If you use your computer a lot at night I strongly suggest you check out this software: well I can't post a link apparently but just google f.lux
It shifts the all colors on your screen more towards the red spectrum and makes it MUCH easier on your eyes. You can set it to come on at sundown, but I keep it going all the time. The color shift isn't noticeable at all after a minute or so. And I've definitely found that it makes it easier to go to sleep right after getting off the computer.

Although like brigid said, the best way to do it is to not be on your computer for a few hours before you go to sleep.