Don: Hey Ya?l, did you know that people with red hair need more anesthesia during surgery than other people? Ya?l: Oh, c'mon Don, that's just another superstition about redheads--like redheads have hotter tempers. Back in the Middle Ages they used to think that people with red hair were witches. D: But I'm not being superstitious. Dozens of studies have shown that it takes abouttwenty-percent more anesthesia to knock out redheads than it does people with other hair colors. Y: Why? D: Well, it's all about pigment. Y: You mean the particles that determine the color of hair and skin? D: Right. So the amount of pigment you have is controlled by a hormone in the brain. Redheads have more of this hormone--and that matters because the pigment hormone is also involved with pain perception. So for some reason, because redheads have an abundance of this pigment hormone, they're more sensitive to pain... Y: ...which is why it takes more anesthesia to knock them out. So does this matter in any major way? D: Well, I guess it does if you're a redhead. But it's not like you have to be worried about waking up during surgery, screaming in pain. Surgeons and anesthesiologists are well aware of the phenomenon. Because, Yael, it's science, not superstition. Y: Touché.