I think many of these types of addictions are a psychological dependence as a result of subliminal influence or programming. For example, if you play a game extensively then go to bed later you may find your mind throwing images or thoughts about that game at you before you go to sleep. It's like working on a production line in a factory - doing the same thing repeatedly. You try to go to sleep in the night only to find that in your mind it's almost like you cannot help thinking about doing that job over and over again, as though you are becoming a robot. of course, this is exactly how subliminal persuasion/programming/mind control etc work.