I've been photoreading for 1 year 15-20 books daily, had numerous spontaneous activations, and I haven't been ill since then, so, that's all about the dangers of Photoreading.
Anyway, Photoreading is definetly healthy, because you won't have to spend hours and hours on preparing for an exam, mugging
sometimes foolish thaories, and do badly on an exam. Instead, you will have plenty of time for other healthy activities like doing sports, you will have good marks, and last but not least, no stress, which is also again, healthy.