The Effects of Cold on the Human Body

Wouldn’t it be nice if we could pack on a few extra pounds every November, dig a deep hole and take a nap until April? Sadly, humans aren’t equipped to hibernate. Luckily, your body is well-equipped to handle seasonal extremes in temperature.

We’re better designed for staying cool when it’s hot than for staying warm when it’s cold. That’s why so many people buy economy radiators each year to weather the weather. Few things are as comforting as a warming blast of heat on a cold, wintry day.

Our bodies are extremely sensitive to cold temperatures. We have an array of built-in defense mechanisms to conserve heat and keep our body core at the right temperature. It doesn’t take too long to overwhelm our natural reaction to the cold. When that happens, bad things usually follow soon thereafter.

Your Internal Thermostat

Just like a car, you have your own on-board thermostat called the hypothalamus. If any part of your body gets cold, the hypothalamus takes notice quickly and performs a series of heat-conserving movements to protect you. This little gland in your brain is dedicated to maintaining the temperature of your core, often at the risk of damaging other parts of the body. There’s no need to flip a switch or rub your hands together. The hypothalamus kicks into gear involuntarily as soon as it senses a drop in temperature.

How well your hypothalamus works depends on a few factors. Any underlying conditions like diabetes or hepatitis could undermine effective heat retention. Your age and general health also play a role in how well and quickly your hypothalamus reacts to a drop in core temperature. Little by little, it starts a series of reactions designed to keep your core warm—even at the cost of a few fingers or toes. If your hypothalamus becomes overcome by the cold, the likely outcome is frostbite followed by death.

Symptoms of Excessive Cold on Your Body

When you first become cold, the hypothalamus shrinks the blood vessels in the skin to halt excessive loss of heat. To generate heat, your muscles start shivering. That makes your skin appear pale and feel cold to the touch. As you shiver, your teeth will chatter along with your muscles. Your body hairs will stand on end to create a pocket of warmth around the body. If your core temperature continues to decrease, the resulting effects get more and more serious. Here’s a list of what can be expected at different core temperatures.

• At 35 degrees Centigrade, you’ll begin shivering. That’s the first sign of mild hypothermia.
• You’ll feel confused and slur your speech at 34 degrees C.
• At 33 degrees C, the shivering ceases and your muscles stiffen. The pulse becomes slows and weakens.
• Drowsiness sets in at 32 degrees C.
• Severe hypothermia begins when your core temperature reaches 31 degrees C. At this point, your response levels are low.
• You’ll lose consciousness when your core reaches 30 degrees C. Your pupils will also dilate.
• At 29 degrees C, you’ll have no detectable pulse.
• You’ll appear to be dead at 28 degrees C.
• Death occurs if your core temperature reaches 26 degrees C.

What You Can Do to Stay Warm

Because our body is poorly equipped to handle the cold for a long period, it’s important that your behavioral responses pick up the slack. Layering clothing, exercising and eating high-energy food will help produce heat. Having a warm dry place to hunker down is a great advantage too. When the weather outside is frightful, curling up with a good book in an overstuffed chair is delightful, especially if you’re sitting next to an electric radiator.