Radiation is a well-known problem. More radiation is emitted by the back of the monitor than the screen, so you, your co-workers and family members should never sit close to the back of your computer. Another hazard is the headache produced by the almost invisible ’flicker’ of the monitor as the image on screen is refreshed. The solution is to increase the refresh rate of the monitor to at least 75hz. Your monitor driver or control panel should offer you a choice of refresh rates. To find out if your monitor is flickering, pay attention only to the view in your peripheral vision. If you see a faint flicker, or find yourself getting frequent headaches, increase your refresh rate,reduce the contrast on screen, sit further from the screen, and increase the ambient lighting around your workstation. Standard fluorescent lights also flicker and can cause headaches or dizziness. If you can, use reflected light from halogens or daylight-spectrum fluorescents - shine the light onto the ceiling or wall, never toward your eyes. Best of all is reflected daylight, but don’t allow glare on the screen. The way you position your head is also important. Your monitor should be placed below the level of your head, and tilted slightly upward, so your gaze is slightly downward, putting your neck in a more natural, relaxed position.
Note: NEVER work past the point of discomfort. Stretch out for ten minutes - right now - save your hands, arms, back and maybe your career.