Why are women more sensitive to cold than men?

The energy crisis and calls for sobriety for the winter of 2022-2023 have brought debates about comfort temperature to the fore. Although the government has asked, since the beginning of the school year, that temperatures not exceed 19°C in offices and homes, everyone has been reminded of the obvious: we are not all the same during periods of low temperatures.

In fact, numerous scientific studies confirm the intuition that women are more sensitive to cold than men. The ideal room temperature is, according to various research, between 22°C and 24°C for men compared to 24.5°C and 26°C for women. If the figures differ, the observation remains the same: there would be approximately two degrees of difference in comfort between the two sexes.

Male hormones inhibit the sensation of cold.

These inequalities in feelings depend on multiple factors, such as age, state of stress, fatigue, metabolism and hormonal state, explains Dimitra Gkika, professor of physiology at the University of Lille.

Therefore, thermogenesis (mechanism of increasing internal temperature) and thermosensation (sensation of external temperature) can fluctuate under the effect of hormones. “We did the experiment on mice and rats, says the researcher. When we took away their testosterone, through castration, the males became more cautious. And when we gave them testosterone again they recovered their initial thermosensation: they were less sensitive to cold. »

Testosterone inhibits the TRPM8 channel protein that detects ambient cold through nerve endings under the skin.

Scientists have shown that testosterone inhibits the TRPM8 channel protein, which detects ambient cold through nerve endings under the skin. Thus, the level of this hormone in the male body will determine thermosensation. This phenomenon explains why older men feel colder than younger men, since testosterone levels decrease with age.

On the contrary, in women, estrogen noticeably thickens the blood, which does not flow as easily to the extremities. A study from the University of Utah showed in 1998 that hand temperatures were 1.6°C lower in women than in men. Estrogen also influences the suprachiasmatic nucleus, a part of the hypothalamus that controls thermoregulation.

In addition, the release of progesterone during ovulation contributes to warming the internal temperature between 0.3°C and 0.7°C, which makes a woman’s body more sensitive to external cold. A similar phenomenon is observed among women who use the contraceptive pill.

Fat layer, muscle mass and metabolism.

Furthermore, there are mechanical explanations for this difference in sensitivity: muscle masses (which generate heat) and fat masses (which do not) influence the sensation of temperature. However, women have on average less muscle mass. In contrast, the fatty layer that separates the muscles from the naturally colder skin is thicker in women.

Women’s metabolic rate, or the amount of energy the body burns at rest, is also lower than men’s below 20°C, a 2021 Chinese study found, with many factors that may explain the differences. statistics in sensations. significant variations at the individual level.

This propensity for women to find solace in a warmer atmosphere than their male counterparts could be explained by evolutionary biology. This discrepancy is seen in many endothermic (body heat producing) birds and mammals, notes a 2011 Israeli zoological study.

Among their various hypotheses, the authors propose that females have a greater need to protect newborns from low temperatures and that natural evolution has favored females who are less able to endanger their offspring by exposing them to temperatures that are too high. hard

Thermal standards to review

However, we must be careful not to reduce supposed female reluctance to a purely biological issue. Women’s more pronounced discomfort in winter is also due to social decisions, particularly thermal norms designed by men for men.

Dutch researchers observed in 2015 that the most common air conditioning devices target a man in his forties and weighing around 70 kg. “This overestimates women’s metabolic rate by 20% to 30% on average”explained to Telegraph one of the study’s authors, Boris Kingma, of Maastricht University Medical Center, the Netherlands.

“The current notion of thermal comfort focuses on men, but it is a more general scientific problem,” explains Dr.^r Gkika

Thus, the ideal temperature in offices is arbitrarily set between 20°C and 21°C, while for women it would be around 25°C. The authors advocate a new thermal comfort calculation system that takes into account differences between sexes, but also age and physiological characteristics, such as thinness or obesity.

“The current notion of thermal comfort focuses on men, but it is a more general problem in sciencecomments Dimitra Gkika. In many studies, for example to develop drugs, the tests are based on the male body. But in recent years the scientific community seems to have become aware of this problem. »

Does the comfort gap between men and women mean it’s impossible to find a temperature that suits everyone? Not necessarily. In 1972, three Scandinavian researchers conducted a study in two high school classes. “For a mixed population, the “optimal” temperature is one at which the proportion of girls who are too cold is equal to the proportion of boys who are too hot.”they explained. “This point in the current data is 24.3°C, a temperature at which 16% of girls were too cold and 16% of boys were too hot”the experiment concluded. Scientists also noted that it is easier to get dressed when it is cold than to take off your clothes if it is too hot.