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Redheads really do suffer more than blondes and brunettes. It takes a fifth more anaesthetic to stop them feeling pain, Edwin Liem of the Outcomes Research Institute in Louisville, Kentucky, found when he looked at how much desflurane it took to stop blonde, brunette and redheaded women responding to 鈥減ainful stimuli鈥�. Liem says there is an explanation. Skin and hair cells have surface receptors that regulate pigmentation. These molecules are less sensitive in redheads, so they produce more of the hormone that activates the receptor. But the same hormone also activates a brain receptor that increases sensitivity to pain.