The relationship between cold sensitivity and menstrual cycle in Japanese women under normothermic conditions

Many Japanese women report experiencing sensations of cold in their daily lives. We conducted a two-part study to determine whether the common complaint of coldness changes with menstrual cycle in women. In the first part of the study (Part 1), we conducted an Internet survey that included 627 women aged 15 to 69 years. Participants answered a questionnaire about the relationship between coldness and menstrual cycle. The questions regarding coldness were used to classify participants into a cold-sensitive group (C group, n = 273) and a normal group (N group, n = 354). In the second part (Part 2), we surveyed 20 young adult women (C, n = 10; N, n = 10) on the cold sensation of 11 body parts. Furthermore, we tested cold sensitivity in the luteal and follicular phases at room temperature (25 ± 1 °C). Cold sensitivity was evaluated by calculating the slope of the relationship between thermal sensation and hand skin temperature during hand cooling in water (from 31 °C to 23 °C). In Part 1, no association was found between the number of applicable coldness-related questions and age. The highest percentage of respondents in both groups answered that “coldness is not related to menstruation” (C, 64.8%; N, 48.0%). In Part 2, no difference was found in the cold sensations at 11 body sites between the luteal and follicular phases in the C and N groups; however, a decrease in sublingual temperature (-0.28 ± 0.22 °C) was noted at the onset of the follicular phase. The cold sensations at 31 °C in the precooling period were significantly stronger in the C group than the N group under both menstrual cycle conditions, whereas cold sensitivity in the hand was similar between the luteal and follicular phases in both groups. These findings suggest that changes in body temperature with menstrual cycle do not affect overall cold sensation or hand cold sensitivity, regardless of the presence or absence of cold constitution, under normothermic conditions.