also, the issue with blood pressure is that when you body or mind is stressed, your heart rate goes up, then comes down when you calm down. With this syndrome, the heart rate overshoots the come down, and you faint. My doctors told me several things make it more likely for this to happen including not enough sleep, hunger, dehydration, and lack of salt. a long car drive without enough food or sleep would definitely do it.
hi
I hope you found an answer since 2008, but since I'm searching this site for my own answers about neurocardiogenic syncope, I thought I tell you my experiences. I have had this condition my whole life. As a child I often fainted, and in high school I finally got the tilt-table test. I got beta-blocker medicine that helped I guess, but stopped taking them 10 years ago after 2 episodes that were obviously not prevented. since then I have followed the advice of several web sites in voiding situations that cause the fainting. For me it could be most prolonged bodily stress (a hot room, even while eating at restaurants, shock etc). If you feel bodily uncomfortable, it's best to lie down with your knees raised. In the last 6 years, I've only had 3 episodes, (2 of them in one night), and all 3 were due to a high fever and food poisoning.