Thank you very much for posting this. Holy cow.
I had a slight brain injury in college, a concussion. Everyone was taking care of the urgent cases, so it took a while to realize that I was no longer tracking anything beyond five minutes at a time.
I almost remember a dream-like experience of sitting in the Emergency Room under observation: they made me sit upright, when I so desperately wanted to lie down and sleep. A good friend sat with me through all that and throughout the night, waking me up every half hour or so. Each time he did so, I would be experiencing the whole shock and fear all over again, asking the same exact questions. After some long hours of this, I "woke up" and started to have a continuous narrative.
I will never forget waking up, staring at the hospital ID tag on my wrist, with the date, May 27th... I could not believe it. I was missing six weeks. What the hell?
I had to sleep a lot that week. In the months that followed, a flash of memory would surface, like a fish jumping out of the pond: a fleeting, flash of silver. I would grab my pocket day planner calendar, and mark down the date that memory illuminated. And so over that summer, I got back almost everything except those final few days before the fall.
It was a year later that I got back the day, just an hour or so before the crash.
First responders said they saw that kind of thing all the time, with guys who had too many beers in them when they whacked themselves in the head. I hadn't had alcohol at the time, but it was college, I bet there was some chronic sleep deprivation in there.
Did I fully recover? I have no idea. It's me. My self.
(The following semester, I had a Philosophy of the Mind class, heavy stuff, Paul Churchland and Professor Searle.
I am actually somewhat thankful I have had this experience, for it is a visceral perspective I cannot imagine inducing on purpose, in a survivable way. Acid or peyote? I don't know. I never tried. Not interested. I've had my ride.)
I absolutely feel that good physical condition -- it was a relatively athletic phase for me -- contributed to the shape of my recovery. And the brain challenges of software and electrical engineering (and philosophy)...
I certainly feel way dumber now, and indeed I flunked half my classes that following semester. But I've had doctors administer IQ tests since, and have gotten the impression that that number didn't change very much.
A good friend of mine has had a life-altering stroke some months after a nearly fatal bicycle crash. His stamina and conditioning still sees him riding as much as 100 miles each weekend, but can no longer speak clearly or walk without some support.
My experience is by no means comparable to his, or to yours. It just drives home the tenuous nature of my experience of reality. It's not just a philosophy class.