I do not seem to have nightmares anywhere near as frequently as most people. In fact, I have difficulty remembering a dream that was even vaguely unpleasant. The actual visual material of the dream is, on occasions, fairly revolting, or would be if it were reality. However, somehow in the dream I know it is fantasy, even to the point of usually being able to control and modify it. Thinking quickly, I can recall only one dream which gave me a fright, and it was very simple.
I dreamed I woke and reached for a drink of water from the glass I used to put on the bedside table every night. In the total darkness, I felt a large hand grab my wrist in a vice-like grip. A few seconds later I really did wake up, and it took considerable effort of will to reach for the glass of water !
If I have eaten too much food, or food of the wrong sort, I invariably have a dream about very grubby lavatories. Without going into specifics, the symbolism is fairly obvious. Too much ice cream, in particular, produces this effect almost without fail.
On the more pleasant side, a dream I enjoy very much is one in which I float up out of my body, go about the house, then the street, then the world. I fly and bounce around everywhere, entering houses through walls and frightening people. The dream has a recurring variant wherein I revisit an imaginary location many times, each time "remembering", or perhaps dreaming that I am remembering previous visits and experiences. One such went on every couple of weeks for many months until I could practically draw a map of the place. On other occasions I appear to fly in time, and meet people of one historical era. There are probably inconsistencies in the detail, but the whole atmosphere is supremely realistic. The piano piece I posted in the Audition Room, "Ellen Lauderdale", was written immediately after a particularly vivid "trip" many years ago, to what appeared to be Victorian England, where I met a woman of this name.
I think nothing actually happens outside my brain, but the brain is a marvellous thing. I can fully understand the origins of such ideas as astral travel, past lives and other mystical states. Jung went as far as to say that we should all construct our own religious myths from the foundations of our dreams.