Broadly, sauna seems to confer its benefits through the effects of heat on the cardiorespiratory, musculoskeletal, and integumentary (skin, hair, and nails) systems, among others. More specifically, sauna has been shown to reduce oxidative stress and inflammation, modulate immune and autonomic nervous system activity, and improve blood lipid and hormone levels.[1] One especially noteworthy characteristic of sauna is its role as a “hormetic stressor”: it puts a mild stress on the body, which provokes cellular processes that encourage repair and protection from future stressors (a phenomenon known as hormesis). Exercise is another form of hormetic stressor, and indeed, sauna and exercise have very similar (but not identical) physiological effects,[2] which include an increase in heart rate (120–150 beats per minute) and an elevation in skin and skeletal muscle blood flow, among others. It’s worth remembering that, alongside its physiological effects, sauna is also simply a relaxing and pleasurable activity (with cultural significance for many); engaging in such activities is likely to benefit health in its own right.