Do you remember the television program "Night Gallery" and the episode "Arachnophobia"? Read on.
I am very nearsighted. Myopia has been my lot in life since early childhood. With eyeglasses, I can see just fine but without eyeglasses, I can't even find an eye chart hanging on the wall much less read one.
I woke up one night some years ago, perhaps a little bit after dawn, and I saw what looked to me to be an enormous spider clinging to one bedroom wall. I saw this thing as being the size of a cocker spaniel, not moving at all, but just there.
I stood up, I woke up my wife and said to her "Judy, we've got to get out of here, right now!" and of course, she had no idea what I was going on about. "What's the matter?" she asked so I told her what I was looking at and after a moment or two she asked "How can you see that without your glasses?"
The logic of that question brought me out of my dreaming hallucination and the giant spider on the wall simply vanished. I can still remember seeing that happen. It was like watching some special visual effect in an old grade-B movie.
After some explaining, we went back to sleep, but oh boy, what a vivid memory that left behind.
While that spider image was there, I was standing upright in the room, I was fully aware of my surroundings and I was carrying on with a conversation. Except for the illusion, I responded to everything as if I were fully awake.
Have you ever heard someone describe an "out of body experience"? I once knew somebody who claimed to have had that happen. Quite frankly though, given what happened to me, I tend to believe such an experience is/was a dreaming hallucination, similar to my own.