Why Do Women Often Feel Colder Than Men?

Let the battle of the thermostat begin. Now that the evenings have grown dark and chilly, most people have switched on their central heating. But many are keeping the temperature low to save on fuel bills, which are expected to rise by 42 per cent this year. Home heating can spark fierce disagreement in couples. Some people sneakily crank up the thermostat when their partners aren't looking; others wear woolly hats and gloves indoors as an ostentatious protest at the temperature of the room.

Some people, it seems, feel the cold more than others. But why is this and is there anything we can do about it?

Research is emerging to suggest that our biological thermostats are set to slightly different levels. We all feel the cold to different degrees, depending on our gender, fitness, age, diet, how much sleep we have, and even the company we keep.

Tropical past is cause of cold feet

At the core of the problem of keeping warm lies the fact that we're simply not built for the cold, says Mike Tipton, Professor of Human Physiology at the University of Portsmouth.

"Man is a tropical animal. We evolved on the Equator and have since migrated to all parts of the planet. The only way we've kept warm is by modifying our behaviour: we've learnt to wear clothes, build buildings, make fire. The oldest man-made building has been identified as a 3-million-year-old windbreak, so one of the first things we built was to protect against the effects of windchill," he says.

Professor Tipton adds that we're only 25 per cent efficient, with 75 per cent of the energy we produce being released as heat>. Although we feel hot and cold throughout the day, our core body temperature - that of our vital organs - is always kept at about 37C. Maintaining this temperature is vital to survival: a 2Cdrop can cause hypothermia, a 12C drop results in death.

Our extremities dictate how hot or cold we feel; the temperature in our hands and feet varies widely compared with that of our organs. If our hands or feet are chilly, we'll feel cold. Most of our biological temperature sensors are located in the skin, and we have four times as many cold sensors as hot sensors. Our heightened sensitivity to cold makes a chilly draught invariably feel more uncomfortable than a warm breeze.

And women really do feel the cold more than men, but this is because they are better at conserving heat than men. Mark Newton, a scientist at W.L. Gore, the company that makes Gore-Tex, and a researcher at the University of Portsmouth, explains: "Women have a more evenly distributed fat layer and can pull all their blood back to their core organs."

However, this female heating system means that less blood flows to their hands and feet, and as a result they feel cold. So there is literal truth in the old saying cold hands, warm heart. One theory as to why women have evolved this system, says Newton, is to enable them to survive freezing temperatures. Women carry less fat and muscle mass than men, and so need a more efficient technique of protecting their core body temperature.

Research also indicates that women's perception of cold varies during their menstrual cycle, says Newton, with the core body temperature often changing by more than 1C. A study in 2001 found that women's core temperature rises in the luteal phase (the post-ovulation phase) of the cycle. The researchers also found that women on the Pill have a slightly elevated core body temperature.

But it's not only hormones that can muck around with our biological thermostats; sleep can also affect how chilly or hot we feel. When we are tired we're more sensitive to changes in temperature, says Newton. Our body temperature falls at night, with women reaching their minimum body temperature quicker than men.