I had the cold water procedure done at a GP to flush out an earwax obstruction. It was absolutely horrible, and I don't recommend it for self-testing.

The flushing took a minute or two. Then there was a minute of starting to feel more and more strange, while everyone asked, "Are you all right?" Then, for the next five or ten minutes....

Notice the reference to REM. If you've ever been so drunk as to see the room spin... you have a slight idea of what my eyes were doing. Closing them didn't help. The staff made me lie down, which made no difference -- I was still clinging desperately to the wall, disoriented and frightened out of my wits.

Eventually the vertigo went away, but I still felt wonky for the next few minutes. Best analogy: being woken from deep sleep and asked to do calculus. Only awake.

Life-changing realizations: none. Perhaps you have to be on-topic at the time. I'm not going back to find out.

Hope this at least slows people down a bit.

[Also, blindsight is an interesting tangent.]