I’m a fainter. I’m not ashamed to admit it. In fact, whenever there’s blood or needles involved, I know after much experience that I need to start out sitting or lying down or I’ll end up flat out on the floor. It’s vasovagal syncope — the condition under which a stimulus causes the sympathetic nervous system to dilate the blood vessels, precipitating a rapid drop in blood pressure. With that drop in blood pressure comes a decrease in the amount of oxygenated blood being pumped to the brain, and loss of consciousness. It’s been a long time since I’ve actually fainted, though. Like most people who experience this phenomenon, there are a number of precursors that signal an impending faint: tingling fingers and toes, fuzzy peripheral vision, nausea, lightheadedness and sweating. When I get these signals, I lie down, take some good deep breaths, and start tensing and releasing my arms and legs to get my blood pumping. The feeling usually goes away within a minute or two, and after about five minutes, it’s as though nothing happened.

Here’s the thing, though: it isn’t just blood or needles. I’ve nearly fainted in the dentist’s office, standing at the checkout desk after having a cavity filled. And last week, I almost passed out at the eye doctor’s. Before checking for glaucoma and injuries to my cornea, Dr. Brigham gave me eye drops with fluorescein dye in them to help with the examination. They didn’t do anything to affect my vision, unlike the drops used to dilate one’s pupils, and they stung just a bit, but no more than the antihistamine drops I have for severe allergies. Regardless, after about 30 seconds, I started to feel those tell-tale signs. It was embarrassing, even more so after the doctor commented, “That’s never happened before.”

That got me to thinking: what is is about my body that it can’t distinguish between mildly invasive or uncomfortable procedures, and serious injury? I started to do a bunch of research (because that’s what I do), and I haven’t been able to find a description of anything that matches my pattern of fainting. There’s lots of stuff out there about people who are afraid of needles or who faint at the sight to blood, but that’s not what’s going on with me at all. In fact, I have some empirical evidence to this effect. Several years ago, I had a whole bunch of blood work done, including a bleed-time test to check coagulation. A typical test involves making a small incision on the forearm, and then timing to see how long it takes for the incision to clot under constant blood pressure. To ensure constant pressure, the lab tech put a blood pressure cuff on me, and I take the fact that both my blood pressure and pulse were completely normal right up to the stick as evidence of a lack of any anxiety or fear on my part. As soon as the incision was made, however, my blood pressure dropped and the tech had to pump up the cuff again to bring up the pressure in my arm and ensure the validity of the test.

My sister is a physician, and an email to her prompted the following reply:

You aren’t fearful of these things, but the “noxious” stimulus triggers an exaggerated reflex response… Sounds like you have a response to somewhat invasive superficial stimuli such as a needle poking you or the fluorescein being dropped into your eyes.

This makes me feel a little bit better. I also found an article from the journal, Clinical Autonomic Research, called “Vasovagal Syncope and Darwinian Fitness,” which frames the issue in evolutionary terms. Interesting, and somewhat calming.

What would make me feel much better, though, would be reading something about other cases like mine, where seemingly benign procedures trigger my body’s shock response. That’s part of the purpose of writing this post, so that when someone else searches for stuff about syncope and overreactive reflexes, they’ll come up with something.