About the low blood pressure: I have it in waking life too.
And here’s what I do when my pressure gets too low (=I get dizzy): I sit somewhere flat, the floor, usually, and then I hold my head down between my knees & take deep breaths. That usually solves it in a couple of seconds. If it’s really serious — it gets serious with a sudden change of temperature, getting into real a hot ambient for instance — I take a little bit of salt (really, just a tad), put it under my tongue and suck it until my body absorbs it. That’ll raise your blood pressure a bit.
As for dreams blacking out, I remember a couple of incidents now that you mention it, but I’m not sure they were just like you said, or if I had some sort of black out and now, reading your description, I’m imagining it was more like you described. I’ll have a look in my journals when I’m back to Sao Paulo. At any rate, comparing it to the low blood pressure blackouts doesn’t ring a bell to me, so if the dream ones were really similar to the waking ones, then it’s not the same kind of dream blackout I’ve had.
Losing sight in dreams used to happen to me quite often back a couple of years, when I was a trainee in an institution for the visually impaired, and dealt with blind people at least twice every week. We had had a couple of trainings in which we’d have to wear blinds and test the exercises and techniques we’d later coordinate and teach… often for a whole day, which was extremely unsettling, and quite a branding memory. When that happens, you indeed often aren’t able to get your sight back. You could try some visualisation techniques, like trying to remember shapes and colours, but that could get your vision back just as much as it could bring you into some higher form of hallucination where you see the forms and colours but not a fully-formed dreamscape. (That, too, can be quite unsettling, although if you’re a WILDer, it should be more of the same fun there is to playing with your hypnagogia).
At any rate, if you have the nerves, you should try a couple of “being blind for ‘x’ hours” sessions, then next time you get blind in a dream, your mind will trigger the whole “blindness sensory experience” memories and you’ll be able to move a bit. (Often times I would fall or come across absurd structures in that state, I just don’t think being blind for a while compares to actually developing a whole spacial perception that independs from vision).
Uh, this is getting quite long. If you’re interested in talking, send me a PM, ok? 