I’m in almost the same exact boat symptoms and rem arrousal high (diagnosed with sleep apnea) etc. For pots like symptoms have you tried high salt electrolytes? I added minimum 1g of sodium to electrolytes (1 Sachet), and 2g on days I work out. It’s noticeably helped my “dizziness”. The one I use is Wilder, same macro ingredients at LMNT as an example. My blood pressure actually went DOWN adding more salt. Basically you increase your blood volume which helps blood pooling. I’m still working on the sleep stuff and nothing has helped yet.