For half a century, computer monitors, Cathode-Ray Tubes (CRT's) or C-R Displays (CRD's) have been known to be statistically related to health problems. As soon as they became common and the association became unmistakeable (in the 60's) popular concern was based on radiation - X-rays. All kinds of restrictive legislation was introduced, especially in Europe, to limit the voltage, hence the quantum energy, of X-ray emissions from monitors. Today, the worry is called 'electromagnetic' radiation.
The health problems are real. The association is real. But, the popular attribution of the cause is mostly wrong.
In the 1950's, Hans Selye showed that simple mental stress was a direct cause of serious health problems. In his extreme experiments, he was able to condition rats, by correlation of a red light to applied mental stress, so that the simple lighting of that red light could cause their bodies to spontaneously destruct - they would die.
Stress causes health problems.
So, how do you reduce your stress level at a computer?
A great deal of stress is based on poorly-designed software. I observed countless secretaries rattling away at their typewriters with no problems, then transitioning to the early, unreliable, word processors and turning into tense nervous wrecks. Physical posture had a lot to do with it too - computer monitors are rarely positioned in a way conducive to relaxed body balance. But, a significant amount of computer stress is caused by mis-adjustment of computer displays. That's what this page is about.
How can you reduce your eye-strain stress during ordinary web viewing?
In one sentence: adjust your monitor so that the black text on white background of this page is as comfortable as reading a book under good lighting, and so you can see most squares in the grid below as separate colours.
The 'brightness' control of monitors determines how well the darkest colours are separated. The 'contrast' control then sets how bright the brightest colours are. The adjustment will depend on your eyes, the ambient lighting, and on your software. (Some browsers chop off the brightest part of the colour range for some reason.)
Remember: the "brightness" control sets the dark levels. It must be adjusted first. The "contrast" control then sets the bright levels. It must be adjusted second.
Don't try for perfection. Almost no monitors have enough adjustments to do that unless you use a screen calibrator. Just try for best balance of viewing comfort (low eyestrain) and colour reproduction.
You used to be able to read some of the technical details on which this advice is based by visiting IBM's site on healthy computing. Or, you can spend as much time studying the effects of computer stress on health as I did until I retired...
other notes on computing