Acupuncture decreases pain by increasing the release of chemicals that block pain, called endorphins. Many acu-points are near nerves. When stimulated, these nerves cause a dull ache or feeling of fullness in the muscle. The stimulated muscle sends a message to the central nervous system (the brain and spinal cord), causing the release of endorphins (morphine-like chemicals produced in our own bodies during times of pain or stress). Endorphins, along with other neurotransmitters (body chemicals that modify nerve impulses), block the message of pain from being delivered up to the brain.