This article is from the Ergonomics and Typing Injury FAQ, by Dan Wallach firstname.lastname@example.org with numerous contributions by others.
A. A mixture of fluorescent and incandescent light is usually most
pleasing. The most important aspect of lighting is to reduce glare and
bright reflections from your screen, nearby glass, or shiny surfaces.
Since light conditions change during the day this may require several
adjustments while working. If you smoke while keyboarding, be sure to
clean your screen frequently as water vapor and smoke make a potent film