Most people think of saunas as relaxation or detox—but Sunlighten infrared sauna sessions also engage the body in a way researchers refer to as “passive cardio.” Instead of simply heating the air, infrared waves raise core body temperature and increase heart rate and circulation, similar to the way moderate physical activity does. Watch on as we break down what a “passive cardio workout” means, how infrared affects circulation, and why people are talking about it in the context of broader health