Hydrotherapy is a traditional method of treatment used for disease and injury by many cultures, including those of ancient Rome, China and Japan. Hydrotherapy can be applied in baths, saunas, wraps, and packs. The recuperative and healing properties of hydrotherapy are based on its mechanical or thermal effects. The nerves carry impulses felt at the skin deeper into the body, where they are instrumental in stimulating the immune system, influencing the production of stress hormones, invigorating the circulation and digestion, encouraging blood flow, and lessening pain sensitivity.
(Source: Holistic Online, www.holisticonline.com)