Thanks, Miku and anais.
[[Edit just before posting: As usual when in this state I wrote a lot when I should have kept it short.]]
One of the only things that works is to not use my brain as much, which is very difficult because I've had to shut down the pursuit of so many interests since the TBIs there's little left to eliminate. [I realize that doesn't quite make sense, but can't figure out how to explain better.

(Edit before posting: but, of course, I wrote a lot here to try.)]
I've used most MSTs as 'sleep aids' for years (the less-funny ones provided just enough word-based attention to keep me from circular thinking which kept me awake, and since I watched them so much, they were too familiar to remain interesting enough to keep me attentive [or require effort to process]) so those aren't available. The RiffTrax and other riffings I have require a lot of energy to process, because I have to process both the film and the comments simultaneously (constantly alternating between the two) in order to comprehend the humor. So they are, when I'm like this, exhausting to watch. I will likely try cartoons at this point. Thank you for the reminder, Miku Fan.
These days, if I try to 'do nothing' (like not watch TV or do stuff on the computer) I tend to have thoughts about the multitude of regrets I have. Everything from being unable to socialize (so no potential for dating or a life partner for the rest of my life, unable to visit with my parents in Illinois for almost a decade who are now about 90 years old and clearly getting ready to 'move on', much less have even just short visits with friends), to losing my career that I spent so much of my life attaining, to not being able to read much (because visualizing for a novel is mentally exhausting [though even reading comics is mentally exhausting], and reading more technical stuff is exhausting to comprehend), to the huge amounts of money I've lost because I couldn't think clearly enough to do things (everything from selling things worth over $1000 on eBay for about $50 because I couldn't think clearly enough to recognize what I was doing, to the over 1/4 of a million $ I've lost to the insurance company's avoiding medical reimbursement, to losses even predating the head injuries [where those investments could really help me out financially now, had I held on to them (near-complete Marvel superhero comics I collected in my teens, but sold before moving to Michigan for grad school for neuropsychology training, would be worth 2-3 million dollars now and would make life considerably less financially stressful - plus I just regret getting rid of them)]). And numerous other things I regret and/or get angry about. So 'not distracting myself' with something results in a downward spiral of my mood.
I do try to force myself to listen to very involving music, but can't always manage to do that as I can't even focus on that sometimes. At my best, I can become so involved with music that I don't think about all the regrets, but that happens less when I am in bad shape because I don't have the capacity to process the depth and intricacies of the music I really love at those points, so it becomes background music for the regrets. If I'm subclinically seizing I can't shut my thinking off either, but right now I'm past that point into 'system crash'.
I've likened my functioning (like now) to Windows 95: my thinking fucks up more and more simply from being 'on', until finally none of the programs work worth shit and it has to be turned off for a bit, then rebooted. I'm in the 'have to be turned off for a bit' stage now. But with demands on me for things on deadlines (financial processing [checking VISA statements and prepping info for insurance submissions, shipping out Amazon Marketplace sales, etc.]), and simply for things like 'remembering to eat on time', I often end up pushing myself when I don't have the mental energy for it.
The only thing that really works is try as much as possible not to think and wait it out. Not an easy thing to do. It is like frequently walking on a broken ankle, but trying to put little pressure on it: every additional step hurts and makes it take longer to heal. But this is a perpetually broken brain, so there IS no end-stage healing for it, I can only do 'a bit better' with it over time [and other than the changes I noticed from cutting sugar out of my diet, we're talking 5-10 years for noticing improvements].