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.
But what else determines our temperatures, apart from gender? Diet can make a difference (see box, right), as can a host of other factors, says Professor Tipton.
“People who are fatter tend to have cooler extremities because their skin is insulated from their body heat by a layer of fat. People who are physically active tend to have higher peripheral temperature because they have better blood flow to extremities. Those people who smoke may have lower extremity temperatures, because they may have poor circulation.”
Moreover, how hot or cold we feel also depends on the temperature we're used to living in, Professor Tipton adds. If you spend a lot of time in a cold house, going to a warm house will be a shock to the system, even if others insist that the temperature is normal.
In fact, the people around us, and how comfortable we feel with them, can also influence our perception of temperature.
Feel warm, be warmer
Feel warm and you'll be more generous and trusting, or so a recent study by researchers at Yale University suggests. They gave volunteers a hot cup of coffee or a cold drink and asked them to rate how trustworthy a person looked. Those holding the hot drink rated people as more trusting.
This shows that psychological warmth and physical warmth have close connections in our brain, says John Bargh, a professor of psychology, who conducted the study. “It seems that the same part of the brain, the insular, which is the size of a walnut right in the middle of the brain, handles both sensations of physical temperature and trust in someone else,” he says.
Professor Bargh adds that giving a person a hot cup of coffee is a way of gaining their trust. “What if someone gives me a cup of coffee when I'm buying a car? Maybe it's best to have a cold drink when making a big decision.”
In addition to this study, researchers in Canada found recently that mood can influence how hot or cold we feel. The study revealed that people who are lonely or socially excluded are more aware of the cold. So if you're looking to warm up this year, get social, get active, and get enough sleep.
How to keep warm
Clothing Ditch the big woolly jumper in favour of multiple thin layers. Remember, the more skin on show, the colder you'll feel. Keep warm at night by wearing pyjamas and bed socks.
Food Eating regular meals makes a big difference if you're trying to keep warm, but be sure to include carbohydrates. Amanda Ursell, the Times nutritionist, suggests dishing up stews and casseroles with meat, vegetables and potatoes. Soup is a great winter warmer: try bean and vegetable, lentil and tomato or pea and ham. Porridge makes a cheap, warming breakfast.
Thermostat 21C-24C is the optimum setting for central heating.
Visualise hot places According to research at the University of Portsmouth, imagining a hot place can make you feel warm.Move around Even if it's just to make a hot drink, keeping mobile is essential to maintaining body heat. A quick jig will not only warm you up but will also release endorphins, those feel-good chemicals in the brain.
Warm homes Insulation and double-glazing are key. Most over-sixties will be eligible for the winter fuel payment.
No comments:
Post a Comment