Contrast therapy, also known as immersion therapy or hot/cold immersion, is a treatment that involves exposing the body to a contrast of temperatures, specifically, extreme heat and extreme cold. Using the concept of vasodilatation (which occurs in the heat) and vasoconstriction (which occurs in the cold), this treatment results in alternating the blood from flowing to the internal organs and extremities, which may help reduce swelling, inflammation, enhance your sleep, improve circulation, relieve depression and provide an overall sense of well-being.