A study analyzed data from 256 sauna users and found that sauna use is associated with a lower nighttime heart rate, higher activity, and distinct effects across males and females and menstrual cycle phases. The study used paired t-tests to compare same-day effects of saunas and non-sauna days. The results suggest that sauna use may be linked to better same-day recovery. The effect of sauna use on heart rate is more pronounced in women during the luteal phase of their menstrual cycle.