I can see where the multiple school changes over the last three years could be exceptionally challenging - especially during COVID. When in-class school resumed in 8th grade, the kids also when through 4 math teachers during that year.
I will investigate additional psych support.
I will look for that book! Thank you for all of your suggestions 
My son really is a sweetheart! Truly.
I tell him “I love you, regardless of everything” I try to tell him that regularly.
I try to let him know that I am on his case about the academics because I want to make sure that he is in a position to chart his own course, as much as possible, in this world. He loves to travel, he loves to try unique foods, he loves spending time with me! He and his sister are my world. They hold my heart. I just want to do all that I can to position them to make the most out of their lives - whatever they decide to do with it.
Dad has tired, I believe. My son has told me that he’s trying to get more sleep but his bed is just too uncomfortable. This is what he blames his poor summer school performance on.
I don’t know.
As a stopgap measure, you can purchase an air mattesss for the floor for not too much ($30-$50). They are pretty comfortable. My adult son has slept on them on vacation and sleeps okay.
I hate to say this…but most teenagers can sleep just about anywhere. But yes…an inflatable bed could be good. Or even a decent mattress topper for the bed he has. But really…if he is consistently not sleeping at night, and falling asleep during the day, I’d wager a week’s pay it’s not just the comfort of the bed.
you may ne right… 
Another suggestion. I have a friend who is a public school nurse. She has seen thousands of kids. She knows, before parents often, which kids have what issues, but the school policy is to never say anything other than refer to the kid’s doctor. Many parents really do not wish to hear certain news. If she were asked," if this were your son which steps would you follow first?" She would be much more forthcoming. Just a thought.
Are his friends having similar issues? How well do you know them?
My 19 and 24 year old sons sleep in twin beds (5’10” 185, 6’2” 230). My 19 year old didn’t even want his college dorm mattress topper. My 19 year old definitely has nighttime Xbox issues, is on 3 medications, 1 that helps with sleep. It’s sad to say but I don’t know how to turn off the wifi at night (my husband and I have no need to use wifi at night, we all have unlimited data on our phones but we leave ours downstairs).
Just shut off your modem.
Op- hugs. You sound like a great parent and I know this is very challenging.
BUT- you’ve added a LOT more information since your first post, so I’ll try to respond.
1- Blue lights from screens is a known sleep disrupter. Your son will kick and scream that he needs the clock, the alarm, etc. But “no screens after 10 pm” (and physically remove the laptop, phone, etc. from his room and you can help him select an $8 alarm clock at CVS or Walmart.) He is not getting enough sleep (duh) AND is likely experiencing a growth spurt, and so his bed is uncomfortable, everything is uncomfortable. Most teenagers can fall asleep anywhere, so this is definitely something to discuss with his doctor.
2- Sounds like more than mild anxiety to me. In addition to the “professionals” trying to figure out what’s going on, has he seen a therapist “just to talk”??? Not someone to fix his academic performance, just someone he can talk to, who can help him develop coping strategies when he’s feeling anxious, etc.
3- Since the neuropsych is far out… make sure his pediatrician has checked his thyroid, all the usual physical stuff which can cause fatigue, sleep disruption, etc. I have a friend whose gyn was extremely unhelpful about her fatigue and sleep issues “it’s called menopause” was the response-- who discovered an easily treatable thyroid issue which actually cured her lickety split. I’m not a doctor, but teenagers love to sleep so this is most worrisome thing you have posted.
4-Side by side communication is the key with a teenager. They just don’t respond to “how was your day” or “why are you screwing up?” or even “what flavor ice cream do you want?” other than “Fine”, “I don’t know”, “it doesn’t matter, you decide”. Lather, rinse, repeat. Figure out/recall and activity you both love to do (or one that you tolerate which he loves) and do it together. Reality comes spilling out when you are both engaged and NOT looking at each other (or you are not looking at him, with him braced for an interrogation). This is a great skill for you to learn right now, and it will really help you with both kids.
5- Again, his friendships and his passion for the music industry are going to be key for him going forward. Make sure you’re including at least one friend – his choice- in the occasional family dinner, miniature golf outing. Not every time-- but enough so that his friends want to hang out at your house. Start planning the “dream vacation” once you’ve saved up enough money- Nashville? Check out the concert schedules – does he want to start saving for tickets for some special event for his birthday?
6- Volunteering- you are near a hospital, correct? Will they allow a minor to perform in the pediatric ward? Nursing home in your area- can he show up once a week to lead a performance, ending with a singalong? Not exactly high end studio production, but working musicians take EVERY opportunity to play in front of real live human beings. Has he told his music teacher that he’d be happy to work with less accomplished/struggling students???
You’ve got this. And so does he…
If bed, why not fall asleep in Spanish? It seems some classes not all so I agree I highly doubt it’s a bed issue.
Or you can even have him leave electronics downstairs at night with you.
I work with middle school and high school students everyday. It does not sound like repeating 8th grade will have any benefit for him. Doing the same thing is not going to change a thing. In fact, many do worse in round two. If the school insists, ask to see the collective data of the academically talented 8th grade students they have retained and their grad rates, SAT scores, etc…
In high school, he should be able to repeat any classes he took in 8th grade for high school credit.
You have a lot to sort out to help him figure out how to be self motivated. Covid has just complicated matters for kids. This electronic work at the current school is not appropriate for him and I am guessing he is bored. Having a twin also comes into play with retention concerns, too, and the counselors should be aware.
It is great that you are searching for answers and clearly want to figure out what is best for him. You need to help him self-advocate as well. His voice matters in this decision.
I am absolutely not saying this is happening with your child, but please be aware of the realities that can play out at this age and what you need to be mindful of with drugs and self-medication. There are lots of great, smart kids who stumble a little and then, to cope, are self medicating and using drugs to treat their anxiety and other fears. Make sure he understands his heart conditions, prescribed meds, and how any drugs or alcohol may interact with those.
It is so hard to help them navigate this time. Give him the space he needs and the professional resources of experts and let him know he is loved and that he has your support. You will come out of this stronger and so will he, but you will need the help of professionals to fully determine what is going on.
I want to highlight this because I think it’s important. He isn’t doing the summer work and why is this?
Please don’t tell me it’s because he is sleeping during summer school classes. Surely even the most uncomfortable bed is easier to sleep on than a desk and chair.
In my opinion, this kid needs a very very comprehensive evaluation which included a very comprehensive physical. And I would suggest a neuropsychologist.
Also, I will say…switching schools three times in three years is not on the best interest of most students.
I agree with the direct language @thumper1 shared, as well.
I updated my post above to include that you can not solve this without the help of experts in this field. I realized I did not stress that enough.
Middle school is rocky in the best of times and the past three years have been anything, but that.
Figure out some short term goals with him to prepare him for the school year. Elementary school was probably easy for him, but all of the sudden there are additional executive functions and time management skills needed to learn the content and demonstrate understanding of the standards. This shift is hard for most kids, but even harder when they never struggled to do well before. Math is more abstract thinking and writing requires far more effort to construct complex thoughts.
The struggle is real and it can be small things that cause tension. My son refused to understand the need for revising drafts of his essays - infuriating for all of us 
Work with a professional to pinpoint some areas where there are some simple fixes and gains can be made.
Unlike everyone else, I’m saying forget about the school switches. Not only is it something you can’t change in retrospect, but also it was probably way less disruptive overall than covid. They all went to online school in their bedrooms anyway!
Anyway, you say he has adjusted beautifully socially and is very popular, so social disruption, the worst effect of changing schools, isn’t the problem.
Ha says he doesn’t remember what’s happening in class - they would worry me. That, and the sleep issue. It seems to affect more than just his executive functioning. Because frankly, a kid with a 146 IQ can sleepwalk through school until 8th grade, maybe not with the best grades, but if that were the only problem, they can wake themselves up and apply themselves when it counts, eg when it’s about moving up to the next grade with their friends and all they have to do is not utterly fail.
I’m thinking of my 7th grader who is about to be diagnosed with chronic fatigue syndrome, could be (undiscovered, she never tested positive) long covid, could be post vax syndrome, who just can’t do anything any more, is constantly tired, but can’t sleep. Not saying this is what is going on, but I think there is more to it than “lots of smart kids underachieve”.
It is extraordinarily rare for our local public school to require repeating of 8th grade ( as opposed to parents who choose to retain students due to immaturity). I would think that such a scenario involves no more than 1% of the student body, and should be treated as the huge red flag that it is.
Is this student in a public school? My impression was this was a private school of some kind…parent chosen.
I don’t know, I thought it was public due to the summer school reference…
I don’t know the kid (obviously) and I’m not suggesting that dwelling on the school switches is a meaningful path forward. BUT- and even with Zoom school- switching schools frequently requires a level of organization just to keep up, let alone thrive. Middle School A has homeroom, but the rest of the day is spent switching teachers, classmates, rooms, frequent trips to the locker (or just the living room) to grab the right notebook or handout. Middle School B has most of the class working together for the entire day except for the small number of kids who are pulled out for differentiated instruction in math. Middle School C has all core academic subjects in the morning, and after lunch is when gym, music, etc. takes place. So a kid who is having sleep troubles is in a vague fog during the academic period, but gets a second wind from lunch and enjoys the electives…
You see where I’m going. No, you can’t change what happened. But understanding how the school schedule and setup functions is an important ingredient (in my view) in coming up with a solution.