It may sound ridiculous but it’s a proven fact : red-haired people are more difficult to sedate in comparison to brunettes and blondes.
In 2002 anesthesiologists conducted a study at the University of Louisville in Kentucky. Twenty women between the ages of 19 and 40 participated in the study. Half of them were redheads and all of the participants were with a synchronized menstrual cycle so that none of them would have the benefactor of the increased hormones. All women were given a certain doze of the anesthesia gas desflurane. Afterwards the participants were put through an electric shock whose voltage would be unbearable for a conscious person. If the participant would show any signs of pain, the anesthesiologists would increase the dosage of desflurane.
The study results showed that redheads needed more anesthesia than brunettes did in order to be sedated. Two years later, in 2004, another study took place with the same purpose. Only this time the study showed that redhead men and women alike need more anesthesia than other people. The key was hidden in the MCR1 gene which was responsible for the resistance of redheads’ systems.