The conversation was going smoothly—until I mentioned blood. Fascinated by a recent visit to Body Worlds 3, I was recounting the details of the exhibit to a friend when it began to dawn on me that plasticized cadavers were probably the last thing she wanted to hear about while munching her margherita pizza. I was just getting to the most scintillating part, the full-body nest of infinitesimal blood vessels that were formed by taking each vein—
“Stop.” Shuddering, she slapped down her pizza, steadied herself by gripping the countertop, then U-turned the conversation to a blood-free Picasso exhibition she saw last month.
Blood. For some, the mere thought of it induces an involuntary wave of nausea, and the sight of it can leave them unconscious on the floor before they know what happened. The reaction can pose a serious health threat to sufferers. People who faint in the presence of blood sometimes dread needles and medical settings more than the diseases that ravage their bodies. They may avoid diagnosis or even refuse life-saving procedures.
Our complex relationship with blood stems from a cocktail of evolutionary throwbacks, physiological survival tactics and unexplained neural phenomena. The same person can experience completely contradictory reactions to blood: they’re squeamish at the sight of their own blood, but not others’ (or vice versa); they can watch someone being stabbed but not cut. With blood, the usual rules do not apply.
Most things that scare us—snakes, public speaking, Freddy Krueger—trigger an accelerated heartbeat and a heightened state of alertness. The sight of blood, however, can generate the opposite response. The vagus nerve slows the heart rate, blood pressure decreases and blood drains away from the brain, making some people feel lightheaded and even pass out.
The condition is called blood/injury phobia, or sometimes blood/injection/injury phobia, but the term is a misnomer. “It isn’t really considered a phobia from a psychological perspective,” says Dr. Kris Cooper, who researched phobias at Good Samaritan Hospital in Phoenix. “If asked about their first experience with their blood phobia,” she says, “most people will describe not remembering being afraid. In fact they usually don’t remember much about it. It happened too fast. They often become afraid of blood after the fact, but what they are really afraid of is fainting.” Because this fear of fainting is considered appropriate under the circumstances, the reaction cannot be considered a phobia.
According to a 1998 report by London psychiatrist Isaac Marks, passing out at the sight of blood is a leftover survival tactic that evolved from animals playing dead. When some animals become frightened or witness a fellow species member dead or bleeding, they freeze, their heart rate and blood pressure drop, and blood drains away from their brains and pools in their muscles. They may even slump to the ground, where in a pseudo-comatose state they are less tempting to predators — most of which are fussier freshness snobs than sushi chefs. (Continued on page 2.)