A science-informed look at heat, circulation, stress, and seasonal resilience Cold weather doesn’t just make us uncomfortable — it changes how our bodies function. As temperatures drop, blood vessels constrict to preserve heat, muscles tighten, and the nervous system shifts toward vigilance. Movement decreases, daylight shortens, and many people notice more stiffness, fatigue, low mood, and lingering aches throughout the winter months. Infrared sauna offers a form of passive