I'd like to answer for myself on that one. The specifics of the situation leave little alternative. I awoke to a situation with a number of components.
1) There were strange pressure points inside of my eye sockets and they were moving. Not painful or even uncomfortable, just .. weird. Never before, never since. It was too dark to see, 9:45 pm guestimate under heavy timber in a deep mountain basin, 50/50 cloud cover, before moonrise. Black as the inside of a boot except for a few stars between clouds. I suspect even with light I would have been blind because the vibrations and pressure were mostly in the general area of the optic nerve around the back of the eye.
2) Hyperventilating. I heard very fast, very very deep breathing.
3) The muscles in my face were spasming uncontrollably. Like they were firing randomly without any input from my brain to control / coordinate them.
4) Intense "congestion" .. could not breath through my nose and struggled to breath through my mouth.
I thought I was dying. I thought the hard hike from 2000 feet to 6000 feet had done me in. 5 miles from the road, more from cell service. I did not expect to live.
5) Mid-panic I began to notice that the rhythm of the breathing I could hear felt out of sync with my own chest. I managed an experiment .. I crossed my arms over my chest to be sure it was not rising and falling, then held my breath. The sound continued unchanged. I started figuring and concluded the source of the breathing was not past my feet, that was too far. It was not beyond my head because there was another tent there. It wasn't the guy in that tent 'cause I could hear him move occasionally and the location was wrong. It was, by my best guess, 18-24 inches from my face. I still don't know if it was to my left, my right, or standing directly over me. I was in a low bivy .. would have been possible.
6) I lay there struggling to breath .. I could, with labor, mouth breath .. and trying to figure out just what the [expletive deleted] was happening to me. After a few minutes, there was a soggy thud 25-30 yards outside of camp, then shortly after that, a clean power-knock from about 75 yards away and off maybe 45 degrees uphill and past my feet. The breathing did not change. This means there were <at least> 2, probably 3, "whatevers", not just 1.
7) It was difficult to move but possible. I was thirsty, forced my hand to move to open the tent, get my water bottle, drank about half of it, re-capped it, and put it back.
8) I have low back problems. Eventually as this "event" continued (breathing unabated), I had to roll over to ease the pain. I did this twice.
Some time after that, I think about 45 minutes after I initially woke up, I fell asleep. I woke up about 12:30 or so. The moon was up. The breathing, etc were gone. I had not noticed in the moment how quiet it had been when all that was going on but when I woke up it was very bright, there were bugs and birds making noise in the trees around camp and fish splashing in the lake. There was zero congestion, neither sinus nor chest. No weakness. Nothing amiss at all. The next morning the canteen was exactly where remembered putting it, half full, capped. It was not imagined. That removes sleep paralysis and false wakening from any further consideration.
The only source I'm aware of which is clinically consistent with all of the symptoms simultaneously is infrasound. (I am open to other intelligent suggestions but not to being insulted by attempts to sweep the uncomfortable back under the carpet, which is about all I've experienced so far .. so I apologize if I get a bit prickly.)
.. but that still doesn't account for glowing red eyes. That's something else.
MIB