Maybe concentrating on a task that requires hand-eye coordination and lots of thought for more than 2 hours at a time is not healthy.
Um, isn't that what most
I know I always feel queasy if I've been playing an action game for that amount of time.
Motion sickness when playing 3D games is common; I would hope that you wouldn't suggest that travel by car, ship, or boat is unhealthy because they cause motion sickness.
Do you suffer painful hallucination? -- Don Juan, cited by Carlos Casteneda