OMG!!! this is SO SO INSIGHTFUL HELPFUL THANK YOU!! These are my symptoms, and YES, I can tell people "hey I am on verge of passing out..I see only black dots..get me some gatorade or OJ etc.)...cause I experienced this about 5 times..And yes, my docs have mentioned I am a person who should be adding salt etc. like you.. I am not under any care for high cholesterol or hypertension, or diabetes... I visited a cardiologist and I am now wearing a smart technology heart monitor for 7 daysscheduled for an EKKOcardiogram, a heart ultrasound too, but NOW I will tell my Primary doc what you suggested and ask for this tilt-test which I read about when I googled Syncope and POTS..term I never heard of before. THANK YOU STRANGER!! wishing you peace and will let you know what I find out because now I am afraid to walk right after I wake up from sleeping or resting..fearing I will black out again..btw my heart rate, resting pulse..is consistently low but has been very low recently. take care dear