Your skin is your largest sensory organ and specialized receptors in the dermis, the second layer of skin, react to external stimuli such as heat, cold and pressure by sending messages through your nervous system to your brain that stimulate the release of endorphins.
Endorphins promote relaxation and a sense of well-being, relieve pain and reduce levels of stress chemicals such as cortisol and noradrenaline, thereby slowing your heart rate, respiration and metabolism, and lowering your blood pressure.
Deeper, more vigorous massage stimulates blood circulation to improve the supply of oxygen and nutrients to body tissues and helps your lymphatic system flush away waste products. It eases tense and knotted muscles and stiff joints, improving mobility and flexibility.
Massage is also said to increase activity of the vagus nerve, one of 10 cranial nerves that affects the secretion of food absorption hormones, heart rate and respiration.