This is really the million-dollar question. The easiest answer we can offer, in bio-medical terms, is that no one has a definitive explanation. There have been many attempts to nail down The One Reason acupuncture works, but to our knowledge no one has got it – yet.
In all likelihood there isn’t one factor, but that many reactions going on at once involving different systems – including the central nervous system – that allow acupuncture to have such wide, strong and lasting effects. This can be seen by people predictably being eased out of the “fight or flight” response (sympathetic) into the “rest and recuperate” state (parasympathetic) once needles are placed during a treatment.
If you have been told or have read that there is one factor to account for how acupuncture works, that explanation is probably not the whole picture.
The most commonly referenced studies on the topic of how acupuncture works have been directed and written by Dr. Bruce Pomerantz, an American physician. Through his ongoing studies, he and his colleagues have found that the body produces measurable amounts of endorphins (natural ‘pain-killing’ chemicals) when receiving acupuncture. For a time, this was thought to be the breakthrough understanding for the mechanism of acupuncture’s effect.
In our opinion however, there are limits to this explanation. For instance, his initial landmark study involved some very aggressive acupuncture needling followed by electricity added to the needles. It was only under these circumstances that the measurable amount of endorphins were identified. This does little to explain how much more subtle needling (like the sort seen in most acupuncture clinics) would initiate changes and cause reduction in pain or improve function, for example.
Dr. Pomerantz seems to acknowledge that his research conducted to this point, offers partial explanations.