I am new to Bikram and have also had some low BP effects such as checkerboard and tunnel vision. I have checked out several sources and have altered my breathing which has helped me tremendously. I now have learned to do the following: focus continually on my breathing pattern so that I don’t begin to hold my breath during a pose. I also exhale when coming out of poses that cause low BP symptoms and that has really helped.
The other thing I have learned is that since I am new at this I am just beginning to learn about my body’s reactions to the intensity of Bikram, and I sometimes push myself to hard and end up struggling with breath, nausea, dizziness. I believe that will happen less and less as I become more attuned to my body’s signals.
So far my Sciatica and Arthritis symptoms have been greatly alleviated and I have lost five pounds in my first 2 weeks (4 times/week)
I wish you joy and peace !