Longwave or Far Infrared is the waveband at which water begins to absorb heat specifically well. With our body's averaging 60%+ water, Far Infrared heat is naturally absorbed by the skin. The warmth is readily absorbed by conduction into the tissue and blood, then transported throughout the body. The Sauna experience creates a deep, warming sensation. This directly effects our body's natural recovery processes, down to the cells mitochondria level.