Since there might be a link with the OP's original post, I'll just make a brief comment.
I read the above link through very carefully, and they do seem to seek information from good establishments, but I'm not convinced they're on the right track with the reason for the dilation.
For a long time I've thought the dilation might be the brain's emergency response to over-clamping or restriction caused by other causes. So many factors make sense looking at it this way around.
This doesn't mean any of the link's reported notions are wrong per se, though I'm personally all but convinced there is some psychological factor. I think the combination of triggers is valid, and cheese and chocolate are high on the suspect list. They do seem to need a brain that's ready sprung to react.
Anyway, this is veering off the original topic, and as I said I was reluctant to mention the connection for fear of the concerns it may cause, but being armed with information is probably best.