Also, LCD monitors are very intense and emit the type of blue light wavelength that suppresses the production of melatonin.
This is a cool app that "reduces" this wavelength as it gets darker based on your clock and location
http://stereopsis.com/flux/
Basically, as it gets darker, the color becomes more "warm" (red tones) and the bright white / blue tone increases as it gets brighter outside.
Unless you're doing a lot of color intensive work, this could help you regulate your sleep schedule.