I suspect that partial paralysis is a better description of what is happening. It is not that we are too tired to use are muscles. They just don't work. It is like being shot with a poison dart by a hunter in the Amazon.

I only had one episode of total paralysis. It lasted just for a moment. I didn't feel anything but puzzled as to what was going on. I was aware of not being able to sit up correctly. I was aware that I was not breathing.
I felt no fear, no pain, no sensation of suffocation. Nothing.

That is until I hit the dirt. Galloping along on your horse is not a good time for paralysis to hit.

Most of the time, I do pretty well. I am droopy eyed and my voice goes all wonky and I walk funny. My students think I smoke pot........