They work using different - yet interdependent - mechanisms that make them complementary with each other. Red light therapy is like eating a nourishing diet that builds the body up, but instead of metabolizing food your body metabolizes light to create the ATP needed to restore, repair, energize, and maintain your body. Sauna therapy uses a mechanism called hormesis - aka beneficial stress - to stimulate a "cellular cleanup mode" called autophagy. Basically, imagine a bunch of little Pac Man guys going throughout the body and eating up cellular trash and debris that's been lying around. Our bodies need ATP to do the cleanup, and interestingly the more cleanup our bodies do (through frequent hormetic stress like exercise, sauna therapy and intermittent fasting) the more robust our ATP function becomes, so as you can see they truly are interdependent. If you're wondering about near-infrared saunas, here's what you need to know: The lamps/heaters that deliver radiant heat to the body (which is the point of sauna therapy) usually contain on a very small amount of the wavelengths that break the cytochrome c oxidase bond and free up the body to make more ATP. Near-infrared saunas are beneficial, but not in the same way as light therapy.