[steve86]

It greatly matters, of course, where in the skin the needle is inserted. It is not just a generic chemical response to dermal tissue injury. I have seen this myself in the P6 acupressure point. You get off the correct location by a half centimeter or so and it doesn’t work at all.

[steve86]

Meant to add also that in the case of acupressure there is no tissue injury, just pressure, but it still can work. Also have had success with a headache alleviation point for certain kinds of headaches.

[TigersEye]

The study also seems to skip over the fact that acupuncture does a lot more than reduce pain.