Diving as an Analgesic

While diving, I often fail to notice that I got cut or scraped by coral or a jagged edge of a wreck. Is my threshold for pain higher when diving, or is it my imagination?

Scientists at the Danish Pain Research Center conducted clinical experiments on diver pain, which were reported by Karsten Korener in the South Pacific Journal of Underwater Medicine. Using an electronic pressure algometer, they measured pain by sustaining a known pressure. Then, by increasing the pressure, they find the pain threshold -- where the diver decides that the pain is intolerable and wishes to be released. On the surface and at four meters, they measured pain on the fingers of 14 volunteer divers, who communicated how much pain they felt and when it became intolerable.

They learned that the pain threshold is indeed higher during the dive. It returns to normal back on the surface. In other words, recognition of the same pain is significantly reduced.

So far, they’re uncertain why the reduction in pain, but it’s not imaginary. Nitrogen is a narcotic gas and since it increases in our tissues during a dive, this might offer an explanation. Also, when tissues cool, nerve conduction is lowered, which might explain an increased pain threshold. Or perhaps, a diver simply concentrates and ignores the pain.

But, the data is worth a caution: because the pain you feel underwater will increase on the surface, your injury may be worse than you suspect.