A good explanation of the effects of acupuncture:

"Research by the National Institute of Health has also found that several types of naturally occurring chemicals may be released into the central nervous system during acupuncture treatment, there-by reducing pain.

Studies have shown that acupuncture may alter brain chemistry by changing the release of neurotransmitters and hormones. Acupuncture also has been documented to affect the parts of the central nervous system related to sensation and involuntary body functions, such as immune reactions and processes whereby a person's blood pressure, blood flow, and body temperature are regulated. "