Menstrual cycle affects thermal regulation and comfort

Abstract

INTRODUCTION It is well known that body temperature in female is closely linked with menstrual cycle. We reported that estrogen affects thermal regulation in rats: 1) estrogen is involved in circadian body temperature rhythm; 2) estrogen has an important role in thermal regulation in both the heat and cold. Moreover, in human beings, not a small population of females experiences some troubles in thermoregulation such as hot flash or cold sensation. Estrogen replacement therapy is sometimes effective for the females. In this study, we hypothesized that there would be differences in thermoregulation and thermal sensation, depending of menstruation cycle. METHOSDS and RESULTS Eight female subjects with a regular menstruation participated in this study. Experiments were conducted twice for each subject in follicular (F) and luteal (L) phases, determined by basal body temperature. Experimental condition was 120-min exposure at 23.5°C after a 40-min baseline at 29.5°C. Mean skin temperature decreased and body core temperature increased in both F and L during the 23.5°C exposure. Oxygen consumption also increased in F and L. Based on rating scores for thermal sensation and comfort, L enhanced both coldness and unpleasantness when ambient temperature changed from 29.5°C to 23.5°C. COMCLUSION Although the autonomic thermal regulation seems to be similar between F and L, the menstrual phase may have an influence on thermal sensation or comfort. Estrogen may be involved in this mechanism. [J Physiol Sci. 2007;57 Suppl:S183]