Sony is the latest company to tell users what to avoid when playing 3D games on its PS3 game console, following Nintendo and Samsung. "Some people may experience discomfort (such as eye strain, eye fatigue or nausea) while watching 3D video images or playing stereoscopic 3D games on 3D televisions. If you experience such discomfort, you should immediately discontinue use of your television until the discomfort subsides," the 3D section of the PlayStation 3 Terms of Service reads.

"SCEA recommends that all viewers take regular breaks while watching 3D video or playing stereoscopic 3D games. The length and frequency of necessary breaks may vary from person to person. Please take breaks that are long enough to allow any feelings of discomfort to subside. If symptoms persist, consult a doctor," Sony adds.

Sony also recommends that users should consult their doctor (such as a pediatrician or eye doctor) before allowing young children to watch 3D video images or play stereoscopic 3D games.

Samsung has also issued warnings about its 3D televisions. Pregnant women, drunk people and those who have a history of epilepsy or stroke, should not watch 3-D television because of potential health issues, electronics manufacturer Samsung says on its Web site.

"We do not recommend watching 3D if you are in bad physical condition, need sleep or have been drinking alcohol," one section says. "Watching TV while sitting too close to the screen for an extended period of time may damage your eyesight. The ideal viewing distance should be at least three times the height of the TV screen. It is recommended that the viewer's eyes are level with the screen."