
We studied 59,000 sauna days - the effects are immediate; Nighttime heart rate drops by 5% That's roughly 3 bpm, pointing to a recovery effect that goes beyond movement Women show lower nighttime heart rate on sauna days across the cycle, but the clearest shift shows up in the luteal phase Sauna pushes the body, then the body shifts into recovery Heart rate rises during heat exposure, then cooling brings a parasympathetic response that shows up later that night






























