Been using a piece of software called f.lux for a couple of months now. I think someone made a thread about this quite a few years ago now, but thought I'd post it again as I love it.
f.lux: software to make your life better
Ever notice how people texting at night have that eerie blue glow?
Or wake up ready to write down the Next Great Idea, and get blinded by your computer screen?
During the day, computer screens look good—they're designed to look like the sun. But, at 9PM, 10PM, or 3AM, you probably shouldn't be looking at the sun.
f.lux fixes this: it makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day.
It's even possible that you're staying up too late because of your computer. You could use f.lux because it makes you sleep better, or you could just use it just because it makes your computer look better.
You can enter your latitudinal and longitudinal location and it'll get the sunrise and sunset location for your area and adapt itself to this. Come sunset it will come in to effect. It took me a few days to properly get used to, but now I don't notice it. Makes using the computer at night much more pleasant.