Formerly known as hydropathy, hydrotherapy involves leveraging the unique physical properties of water to treat a wide range of conditions and symptoms, including acne, arthritis, colds, depression, stomach issues, headaches, joint and muscle pain, sleep disorders, and stress and anxiety. The temperature and pressure of water initiate thermoregulatory reactions for therapeutic benefit—to increase blood flow, for example. Hydrotherapy can be delivered via water jets, underwater massage, mineral or whirlpool baths, or hot tubs. Those receiving hydrotherapy may do so by submerging either the entire body or portions of the body. Hydrotherapy also is used in the treatment of wounds—for directed wound irrigation and therapeutic irrigation with suction, for example. Additionally, hydrotherapy may be used in the treatment of burns. For hygienic purposes, this type of hydrotherapy typically involves shower-based techniques, rather than full immersion. A newer form of hydrotherapy, cryotherapy, is especially popular among physical therapists and sports medicine specialists. This practice involves cold-water immersion. Contrast hydrotherapy also has grown in popularity in recent years. This method combines hot-water immersion and cold-water immersion during the same therapy session. Studies have shown that this approach stimulates blood flow and reduces swelling during the acute stages of injury. However, hydrotherapy is often best used as an accessory treatment to standard care.