Question:
My son stims a lot while reading and especially while watching tv or playing video games. Why does he do this and should we restrict his playing of the games?

My Opinion:
I will repeat what I see as the relevant facts here, so you can see where I am getting my opinion.

For books -- he will read, then leave to stim, then return to read, or stim while reading.

For tv/computer game -- he will be fully absorbed and focused, but then when he is finished, he has a marked increase in stims.

Books require mental energy for visualizing plus you have to do all the work, so basically you can control somewhat the speed you take in the information. If you get overwhelmed with sitting in one place, or trying to maintain your focus, or with what you are reading or trying to learn, then you can stim either there while you are reading if it is not too overwhelming, or you can leave and then come back, and the book does not progress without you, so you don't have to worry about that.

For tv/computer games, it generally does all the work for you, or you have to actively participate, so you have to remain in full and constant attention. This takes a LOT of mental energy, at least for me, to sit still for so long, to look at one place for so long, to absorb what is happening, at the speed it is happening since you basically cannot control how fast it happens or even what happens, you have to pay attention 100% of the time or you lose both connection to what is happening and also the facts on what exactly has happened. So you are required to remain focused at all times. Then, when you are finished, all that overwhelming focus, all that activity, just stops. So you have a major transition from mental activity to non-activity, but you are also just transitioning in the first place. So transition in general plus transition in level of mental activity, for me, would equal a very strong requirement for stims to settle down and make the transition.

If you watch your son while he is playing his video games, I think you will be able to find something about his body that is tense or otherwise "stimming", but he will hold the main ones for later when he does not have so much mental energy focused on the game. Maybe his teeth are clenched, his toes are curled, he is chewing on his lip or running his tongue on his teeth, talking or muttering to himself or to the game, his foot is tapping, maybe some internal muscle tension that you cannot see but he can feel, something might be there to help him with his focus. But maybe not, maybe it does require all of his concentration to do the games. I know when I play video games, which is not often, it does take almost all of my concentration, altho I do prefer games that are slower because I get much too overloaded and stressed out when they move fast, I can’t stim enough to maintain my focus so I can’t concentrate to play them for very long, I guess I am getting old.

Therefore, with a book, your son can stim, or leave and come back, when he feels he needs to do it. It will wait for him to return. For the tv/computer, I don't think IT is "controlling" your son's stims, just that he can't do them while he is doing the electronic stuff too, that would require more mental energy than he can spare. So HE controls it, whether or not he is aware he is controlling it at the time, and then it all comes out later. Especially since you say you redirect him to be more appropriate or at least to go in private, but he is having more difficulty in being more appropriate now, because it would seem to me that he is more overwhelmed and cannot control it. The newness of the games or the transition back to school can be an explanation of why he is having more difficulty with this at this time.

I do not think banning these items on school nights would be appropriate, as if it was me, I would see it as a punishment for being the way I am, that I am punished for not being able to control my need to stim. I think limiting the exposure is a good thing to do. I don't know which would be good for your son, whether it would be good for you to allow your son to have his tv/computer time right after school, he is making a transition then anyway and also he is "worked up" already, or if he should have it later in the evening. It might make him wound up again later, and he would have a more difficult time settling down to sleep, but it can also be used as incentive for doing his other work that he is required to do. For me, I think it would be good if I would do it right after school, for a limited amount of time, and then more on the weekends, but for your son it might be different. You would know that better than I would. But the electronic stuff would wind me up, and the book stuff would be easier to settle down, as I would not be all wound up and then need major release, I could get my release as I am reading, as you have noticed with your son. So computers earlier in the day and books later in the day, would be best for me.