If a video game can induce a seizure, which under normal circumstances is harmful, but medically "useful" in situations of electroconvulsive therapy, it is likely that there is potential for there to be software applications that will need to be "controlled bits" just as there are "controlled substances."
There may in a short wait come a time that immersive applications may need to be reviewed by a voluntary panel for safety if they are meant to invoke a physiological response in the human body more than happiness.
It may hit a point that apps may have to be restricted to a prescribed basis because their immunostimulant behavior may move from neutral to active.
An example of such an app would be one that is created to increase immune function. Under normal circumstances, you would not expect an immune system to react beyond optimal, but there is a remote conceivable risk that a digital immunostimulant may invoke a beyond optimal response in someone with or predisposed to an autoimmune disorder.