I have been having these episodes since January.  They are sporadic, never know when they will appear.  There is never the same time of day nor am I doing the same thing when they happen.  My pressure goes as low as 48/30. I will usually just Pass out and go to sleep(a very scary feeling). The episodes will last about two to three hours with the pressure slowly going back up. I feel really lethargic the rest of the day.  I wear a c-pap at night and I think that is why I have never had one during the night.  I am wearing a heart monitor for a month, but cardiologist is not sure  if the heart is the cause of the episodes.  Any ideas or answers?