If you belong to the army of IT guys like me, who stare at monitors for long hours at night, try the program f.lux.
You set your location so that it knows when the sun sets, and it slowly changes the color scheme of your monitor to warmer colors - I currently have it set to 3600K compared to 6200K during the day. It really makes a difference, and if I switch to the regular scheme at night, the monitor feels like a spotlight.