+1 for hydration being a factor. I'm a 100/60 person, and I am susceptible to tunnel-vision and dizzy spells, but I really do not think my BP is the culprit. I notice a direct correlation w/ my hydration level and the dizzy spells. The more hydrated I am, the less likely I am to see black when i stand up. I also try to keep up on my iron intake and B12. It seems like the additional iron helps as well, but I can't know for sure. But I do know i *really* have to keep up with my hydration to keep the dizzy spells at bay.