Most people who can remember their college days with much clarity (such as people still in college) should have the greatest understanding of this situation:
On nights when I go to bed somewhere between tired and exhausted, after going from the lit first floor to the unlit second floor to my room right as the light comes on I experience the interesting phenomenon where even though each item I see is in and of itself clear and in focus, the sensory transitions are too much for my tired mind to wrap themselves around, and the best thing that my brain sees is a vague assemblage of shapes, similar to what people call 'modern art'. As most people with high school educations are aware, the brain does fascinating things to try and map bizarre things one sees into concrete things it understands. Likening to a silouhette of a coat on a free-standing coat-rack being initially seen as a person.
A while back this assemblage of shapes started to take on yet another collage, but this time of more concrete images rather than vague shapes. One example which I will share is sometimes having a full laundry basket in front of the heat radiator would occasionally be seen as an armchair (the radiator being the back, laundry basket being the seat, and the windowsill nearby serving as an arm).
A short time later rather than a collage it became a scene.
After it became a scene, it became an animated scene (changing position in the room changes perspective of peripheral objects, which led to the sensation of animation). Then, an audio track developed. It's not always the same, but it is consistent (the same -types- of sounds. If the sounds were voices they would be by the same person, or a squeaky fan at different speeds, et cetera).
The 'vision' is of something that is not reality, nor do I ever expect it to become reality. Knowing the entire time why I was seeing what I was seeing (though, not knowing why I was hearing what I was hearing) I initially internally-scoffed at the 'visions'.
A couple of weeks ago I saw "The Sting" (Futurama Season 05 Episode 09) for the first time. Summary of relavent parts: Leela is comatoseish and dreaming. In her dreams she dreams that someone she saw die is alive, but keeps telling her to wake up. Eventually she wakes up from the outermost dream to find that the person she saw die was in fact alive (he died in the dream) and was telling her to wake up (from the coma). To relate this to my situation: I have been wondering if maybe the visions I have are a glimpse at reality, and what I think is reality is merely a dream; or if I'm maybe seeing the future; or if I'm crazy; or if this is just, as I started off saying, the brain doing fascinating things with image processing.
I don't really feel comfortable sharing the details of the visions in such a public manner, I simply felt like recollecting that I had them, and if anyone cared enough to read this then they can be enlightened by my level of craziness.