I had the exact same symptoms and was diagnosed with hyperadrenergic POTS . I had to go through 5 cardiologists until someone finally told me that I have POTS. But I had to be seen by a specialist for POTS that checked my adrenalin levels (which were extremely high upon standing) before I was finally diagnosed. Since then I have had many trials of meds but am a lot better controlled as long as I am living within my limited abilities. When you see the Dr Monday make sure you mention " hyperadrenergic POTS". It has a different mechanism than the more common form of POTS as it increases the BP as well as the HR upon standing and is caused by abnormal adrenalin-surges ( do you get shaky, cold, clammy, weak ... ?) I also pass out a lot, maybe your "sleeping" is actually syncope (passing out)?