I found this an amusing info graphics from Wired:

“Practicing good nutrition keeps your mind sharp, your body fit, and your life long. The same could be said for consuming media. (Seriously, knowledge is power.) When you add it all up, the average American spends roughly nine hours a day glued to some kind of screen, and like your diet, quality is as important as quantity. Here are Wired‘s suggested servings for optimal media health.”