When the temperature plummets, your body’s systems are stressed as they struggle to maintain a sufficient internal temperature. Your body’s first reaction to cold is the constriction of blood vessels in the skin to reduce the amount of heat lost and to divert blood to your vital organs. You may start to shiver, which produces heat through involuntary muscular contractions, and your body releases hormones designed to stimulate heat production. When the length of your exposure to the cold is prolonged, however, your body’s core temperature begins to decline and hypothermia results.
Untreated, hypothermia can kill. Early signs include numbness in the extremities and a noticeable loss of coordination. The victim will often shake uncontrollably and show signs of mental confusion or apathy. In advanced stages the patient can become incoherent and unable to walk or stand.
Frostbite is another very real danger when cold weather hits, and it can also be accompanied by hypothermia. Frostbite has four distinct phases: in the first stage, blood vessels constrict, leaving the affected tissue starved for oxygen. When the tissue temperature drops below 24.8°F, the second stage is marked by the growth of ice crystals in the skin, which damage the tissue’s cellular structure. During the third stage, fluid leaks from blood vessels into the damaged tissue, and in stage four the blood vessels clot, cutting off all blood supply and causing massive cell death in the affected area.
Frostbite symptoms are similar to those of hypothermia: the victim feels extremely chilly, with increasing numbness and decreasing coordination. As the damage progresses, fluid-filled blisters form. In cases of severe frostbite, the blisters deepen and become permeated with a purplish fluid. When the tissue is warmed up again, it will often swell and turn darker.
The best treatment for frostbite or hypothermia is to get the victim to an emergency room or doctor’s office as soon as possible. If help is more than two hours away, a frostbite victim’s affected body part should be slowly brought back toward normal temperature in water at 100°F to 105°F, and care should be taken not to allow it to refreeze, since permanent tissue damage would almost certainly occur. For cases of mild hypothermia, try to get the victim moving; exercise generates warmth. Build a fire or get the person near a source of heat. For more severe cases wrap the patient in as many layers of dry blankets or wool clothing as possible, and then add a layer of plastic. Try to keep the victim out of direct contact with the ground.
To prevent cold-related injuries, wear layered clothing to insulate your body against the elements. Avoid getting wet: water conducts heat away from the body twenty-five times faster than air, especially when evaporation is enhanced by a stiff wind. If exercising or hiking outdoors, stop whatever you’re doing and warm the area immediately if you see or feel evidence of a cold injury.
The opposite of hypothermia is hyperthermia, when your body can’t keep itself cool enough to maintain normal function. An early stage of hyperthermia is called heat exhaustion, when an excessive loss of water causes the body’s internal temperature to rise. Someone suffering from heat exhaustion will appear pale and sweaty, and can often be dizzy and experience nausea or vomiting. A victim’s skin will sometimes be cold and clammy. The person should be moved to an air-conditioned building, given water or a sports beverage, and be watched for improvement. If no improvements are seen within thirty minutes, an emergency room should be your next destination.
Heatstroke is hyperthermia gone berserk. With heatstroke, the victim’s internal thermostat, or heat-regulating system, has broken down. Symptoms include complete disorientation, difficulty walking, cessation of sweating, fainting, and unconsciousness. The victim’s skin will be hot and dry, and his pulse rate may rise as high as 160 beats per minute. Because heatstroke can be fatal, a victim should be cooled down as quickly as possible, using ice packs or cool water splashed on the skin. The person’s legs should be elevated, and plenty of fluid should be given. If no medical facilities are nearby, the victim should be wrapped in wet clothing or bedding before transport to the nearest hospital.
Less severe than heatstroke or heat exhaustion are heat cramps, but they can still ruin a perfectly good day outdoors. Heat cramps feel like a severe muscle pull in the calves or other muscles, and are usually brought on by exercising in hot weather before you’ve built up enough conditioning; a lack of fluids can also play a part. The best remedy is rest in a cool place.
Sunlight is essential for human survival; it aids in the production of vitamin D, which prevents a disease called rickets, and is a potent mood elevator. But even limited exposure to the Sun’s rays can cause sunburn in fair-skinned people and children, and long-term exposure can create wrinkles and leathery skin as well as a very dangerous form of cancer called melanoma.
Your skin contains melanin, a pigment that gives skin its color and provides some protection from UV solar radiation. The more melanin in the skin, the longer it will take to burn: light-skinned people may burn in as little as fifteen minutes in the noonday sun, while darker-skinned people can stay out for hours. But eventually even the most UV-resistant skin will suffer damage from prolonged exposure, and unlike a burn caused by a match or hot stove, a sunburn tends to sneak up on you. The pain may not peak until six to forty-eight hours after exposure, and then your skin can swell, blister, and peel for days.
Doctors recommend wearing a sunscreen with an SPF factor of no less than 15 (about the same protection as a cotton T-shirt) when you spend time outside. Studies indicate that most people apply only half as much sunscreen as researchers do when they’re assigning SPF numbers, so be sure to apply the lotion liberally and reapply it after swimming or heavy perspiration.
Umbrellas, hats, and clothing are other good ways to prevent sunburn, and it’s a good idea to avoid the beach between 11 a.m. and 1 p.m.—that’s the time when the Sun’s UV bombardment is at its daily peak. Unfortunately, the effects of solar radiation are cumulative, so the more time you spend in the Sun, the more likely it is you’ll eventually have skin problems.
There is now little doubt that long periods of gray, gloomy weather can bring on a crushing case of the blahs. This even has a name: seasonal affective disorder, or SAD for short.
Symptoms of SAD include carbohydrate craving, weight gain, oversleeping, and other depressive symptoms such as lethargy and a feeling of hopelessness. The first signs of SAD usually make an appearance in October or November and begin to subside in March or April as spring approaches. Doctors got their first clue into the causes of SAD when some of their patients complained that their depression increased during overcast periods, and they began to look at the effects of different light levels on mood. They found that SAD is more widespread the farther north you go, so people in Seattle are seven times more likely to have it than Miami residents.
Scientists now think that the release of the hormone melatonin by the brain’s pineal gland, a pea-sized structure just below the brain, has a hand in bringing about the change in brain chemistry that causes the symptoms of SAD. Melatonin causes tiredness and seems to be related to our body’s biological cycles—called circadian rhythms—although the exact nature of the link is still unclear. What is known is that SAD patients have more melatonin during a depressive episode than people who are not depressed, and that phototherapy returns their melatonin levels to normal.
It’s now thought that four to six out of every one hundred people may have SAD, and studies show that it’s four times more common in women than in men. The malady doesn’t usually begin until after a person’s twentieth birthday, and the older you get, the less likely you are to contract the disorder.
It’s been known for centuries that animals respond to changes in weather: bears hibernate, geese fly south for the winter, and squirrels gather nuts. But for humans, the weather’s effect on mood was often chalked up to crankiness or a generally bad attitude. Now the new science of biometeorology is helping explain how climate can have a very real effect on both physiology and psychology, speeding the development of new treatments for weather-related ills.