Why women feel colder than men: research offers an answer

Just as women's and men's bodies differ in structure, so does their ability to sense temperature. The same room temperature can feel quite different to two people. In cold weather, or under air conditioning, women in particular feel colder than men.

Many have long treated this familiar reality as mere habit, but medical science says otherwise. The clear evidence for why women's bodies prefer a warmer environment than men's lies in our blood circulation, hormones and metabolism.

A recent groundbreaking study has brought the real reason behind this everyday phenomenon to light. Most surprisingly, the hormone testosterone is the main force pulling the strings behind this difference in temperature perception.

Countless nerve endings lie beneath all our skin, and their job is to carry the sensation of cold or heat from the outside environment to our brain. In the words of Dr Michael Caterina, a neuroscientist at Johns Hopkins University in the United States, the protein sensors inside the skin can be compared to tiny electrical generators.

As soon as the temperature of the environment changes, these generators switch on, and charged ions enter our nerve cells and send electrical signals to the brain. It is on the basis of these signals that we decide whether to sit under a fan or wrap ourselves in a blanket.

Alongside humans, other animals such as birds and mice show the same pattern: females prefer a slightly warmer environment than males. To unravel this mystery, researchers set up a remarkable experiment.

They placed 30 male and 27 female mice on two plates of different temperatures. One plate was kept at 33 degrees Celsius, while the temperature of the other was repeatedly raised and lowered.

Watching the mice's movements on camera, the scientists found that when the plate temperature was raised to 38 degrees Celsius, the female mice spent far longer on the hot plate than the males. Calculations showed that the males' favourite temperature was 32 degrees Celsius, while the females' was about 36 degrees Celsius.

In other words, women's skin sensors need 4 degrees Celsius more temperature to become fully active than men's. Since there was no difference in the mice's internal body temperatures, it is clear that the structural difference in women's skin sensors is why they naturally enjoy warmth more.

The researchers then decided to dig deeper. They wondered whether the body's sex hormones had a hand in this difference. They gave a group of male mice drugs that stop the body from producing testosterone.

After a few weeks, a magical change appeared. The male mice that previously did not want to stay in the heat began spending more time on the 38-degree plate, just like the females. Conversely, after female mice were given testosterone, their natural tendency to seek warmth disappeared entirely.

Most strikingly, the female hormones estrogen and progesterone had no effect at all on this sense of hot and cold. In other words, testosterone is running the whole show. According to Peter McNaughton, a pharmacologist at King's College London and one of the study's authors, testosterone does not strike the temperature sensor directly; rather, it changes our sense of hot and cold by influencing gene activity over a long period.

It may sound like merely an amusing scientific fact, but its impact on our daily lives is far-reaching. Researchers say the very same kind of sensors work in human skin. This discovery could help design office buildings and spaces that are comfortable for everyone, women and men alike. It could even open a new horizon in treating people who suffer nerve pain and whose sense of hot and cold is far more sensitive.