Thermostat wars are already raging in homes across Britain, as women turn it up and men turn it down. Female workers shiver in offices as male co-workers stroll by in shirtsleeves, and mums bundle up in puffer jackets for the school run, while dads shrug on a light jumper.
But why? Are women just fusspots, forever whinging about the non-existent chill while men are naturally brave and hardy warriors, content in a T-shirt as the temperature plummets?
Or is there a scientific reason for the well-recognised disparity when it comes to who's blowing hot and cold?
Of course, there's a scientific reason – and a new study has proved it. Researchers from Israel's Tel Aviv University studied bird and bat species to see if there was a difference in response to temperature.
They discovered that male animals preferred lower temperatures, and suggested that their findings showed a variation in the heat-sensing mechanisms of the sexes.
“Our study has shown that the phenomenon is not unique to humans; among many species of birds and mammals, females prefer a warmer environment than males, and at certain times these preferences cause segregation between the two species," said Dr Eran Levin, co-author of the study.
“In light of the findings, and the fact that this is a widespread phenomenon, we have hypothesised that what we are dealing with is a difference between the females’ and males’ heat-sensing mechanisms, which developed over the course of evolution.
The difference was similar to the different ways in which the sexes experience pain, said the authors. Neural pathways in the brain and hormones may both play a part.
Watch: Women more productive at work if office temperature is warmer, study says
Previous studies have suggested women feel the effects of the office air-conditioning more readily because of a variation in their average metabolic rate.
Evidence has also suggested women have different sensory mechanisms, meaning that they experience temperature differently than men.
The researchers also thought that female mammals may prefer warmer temperatures in order to protect their offspring before they are able to regulate body temperature. The huge study used data collected over almost four decades, and birds and bats were chosen for being highly mobile, to make it easier to spot when separation was taking place due to temperature.
"The bottom line is, going back to the human realm, we can say that this difference in thermal sensation ... is meant to make the couple take some distance from each other so that each individual can enjoy some peace and quiet," said the authors Dr Levin and Dr Magory Cohen.
“The phenomenon can also be linked to sociological phenomena observed in many animals and even in humans, in a mixed environment of females and males: females tend to have much more physical contact between themselves, whereas males maintain more distance and shy away from contact with each other.”
But while space is all very well, there are simpler reasons why women might feel colder than men as temperatures drop.
Read more: Is it normal to feel cold ALL OF THE TIME?
GP and author of Managing Time In Medicine Dr Ed Pooley explains: "Evidence shows that women are more susceptible to lower temperatures as their blood vessels tend to constrict sooner in response to cold than those of men.
"The consequence of blood vessels that constrict more readily is that hands and feet feel colder and women feel colder sooner than men in low-temperature environments," he goes on.
It seems it's to do with hormones and body mass, like so much else.
"It is thought that this is due to a combination of the effects of oestrogen and the relative proportions of muscle and fat tissue that are present in the average man or women," he explains.
"Women have more fat that sits between muscles and skin and so the skin feels colder as the fat protects the vital organs from the cold but increases the distance between blood vessels and the temperature sensing nerves within the skin."
Research from Dr Mike Tipton, professor of human and applied physiology at the University of Portsmouth, also highlighted the differences in skin blood flow between men and women.
"We have conducted studies where we have taken men and women into a warm environment, and then cooled that environment," Tipton says. "Women have a much more sensitive vascular response to the cold, which means they shut down their blood flow sooner, tighter and for longer than men.
Read more: Four reasons you might always feel cold
"The reason for this is that women are just more sensitive to that peripheral cold stimulus. The hormone oestrogen also contributes to making the blood vessels more sensitive to cold."
This is why women are more sensitive to temperature, including sudden draughts, and why women have colder hands and feet, which affects overall body temperature.
"Because women also have more body fat, which doesn't have much in the way of blood supply, it insulates the skin, so their skin temperatures tend to be lower," says Professor Tipton.
"Hand and foot temperature are maintained by blood flow, so if the blood flow is shut down – as is found in women – then skin temperature falls, creating the sensation of cold hands and cold feet, determining your overall level of comfort perception in the cold.
"This means you can have people who have a reasonable chest temperature or back temperature, but if they've got cold hands, they'll feel cold."
There's also the evolutionary explanation. Dr Sarah Jarvis told Patient.info.
"Homo sapiens evolved in the tropics, and dying from too much heat was much more of a risk than succumbing to hypothermia. In those days, men were out getting hot and sticky hunting and gathering while women stayed at home looking after the children.
"That meant men needed highly evolved ways of avoiding overheating, which is where sweating comes in. Men were doing more exercise, which helped keep them warm. Women were also smaller, meaning they had a higher surface area-to-volume ratio - and the surface of your body is where you lose heat from."
So whack up that boiler, women - turns out you were right all along, and you really are colder than he is.
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