Hypothermia occurs when your body loses heat rapidly, to the point where there is a drop in core body temperature below 95?F. This generally happens whenever your body is exposed to cold temperatures for an extended period (typically from several hours to several days). If your skin becomes both chilled and damp, this can accelerate the process. (You can develop hypothermia even at temperatures of 50?F if the weather is especially windy or wet.) Often a person who slips into hypothermia is overwhelmed by drowsiness and may fall asleep, at which point there is a risk of freezing to death.
What puts you at risk
Hypothermia is generally caused by a combination of inadequate clothing protection and exposure to cool or cold outdoor temperatures, especially when combined with wind or rain. Hypothermia can also occur when a person stays in cold water for too long.
Although it is mostly associated with cold outdoor winter weather, hypothermia can also occur indoors during the winter months. Elderly adults may be especially susceptible, particularly if they keep their thermostats set low to save on heating costs. Older people are often less able to shiver effectively, which is one of the ways your body increases heat production to stay warm.
Various medications (notably for sleep and anxiety) and alcohol can also contribute to the onset of hypothermia by interfering with the body’s natural heat-regulating mechanism in the brain.
Being slender can make a person more prone to hypothermia. A slender person usually has a comparatively low level of body fat and therefore less natural insulation from the cold, so body heat is lost more rapidly.
Signs of hypothermia
Any of the following can indicate hypothermia: numbness; excessive shivering, or the absence of shivering when it’s cold; cold skin; fatigue or sleepiness; faint or slow pulse; loss of coordination; slurred speech.
A drastic drop in pulse and breathing rate, or loss of consciousness, are emergency symptoms that require emergency medical care.
Immediate care for hypothermia
Contact a doctor or medical facility as soon as possible if you suspect someone you are with has hypothermia. If not dealt with promptly, hypothermia can quickly become a medical emergency. A hypothermic person is at risk of developing frostbite, and, more seriously, can slip into a coma if body temperature is not restored to normal. If the situation seems severe, call 911 or have someone get you to a hospital emergency room immediately.
If severe hypothermia is diagnosed, the person will be gradually rewarmed over a period of time. This will prevent the rapid enlargement of blood vessels at the skin’s surface, which could affect blood flow and severely impair the functioning of the inner organs.
Take the following steps until professional help is available:
- Warm up. Get the person out of the cold and into a warm room. Remove all wet clothing. If possible, get the person into warm, dry clothing and wrap him or her in blankets to prevent further loss of body heat. (Be sure to wrap the head and neck.)
- Carefully check for frostbite and take appropriate steps to treat it.
- Supply warm fluids. Have the person drink warm fluids like soup, coffee, or tea (but not if he or she is too drowsy to drink without choking or regurgitating). Absolutely avoid alcoholic beverages: they will dilate blood vessels under the skin and accelerate the loss of body temperature.
- Preserve wakefulness. If a hypothermic person is losing consciousness, do whatever you can to keep the person awake, including talking, jostling, playing music, or using some other noise.
Tips for preventing hypothermia
Being properly dressed is the most important step for preventing hypothermia. Wear protective water- and wind-proof outer garments when going outside in cold and wet weather for any length of time. Dress in layers to best trap valuable body heat and insulate yourself. Put on a first layer of thermal undergarments; a middle layer of a synthetic or fleece jacket, or a wool or synthetic sweater; and, for an outer layer, a jacket that’s waterproof, wind-resistant, and breathable, so that moisture isn’t trapped inside.
Mittens are warmer than gloves, since they keep your fingers together. Be sure to wear a hat: It will trap body heat and keep it from escaping through your head.
The following measures are also protective against cold.
- Eat something. Be sure to eat and drink before heading outside in frigid, cold, damp, and windy weather. This ensures that your body will have the necessary fuel it needs to keep going and stay warm. Keep nibbling on high-energy snacks during extended outdoor stays to help maintain body heat.
- Avoid alcohol. Alcoholic beverages interfere with the body’s ability to regulate temperature.
- Keep warm. Make sure your indoor home temperature is in the 70?F range and that you wear adequate clothing at all times.
- Stay inside during severe winter storms. Don’t put yourself at risk in extremes of temperature, no matter how well you’re dressed.
- Get out of wet clothing immediately. Water speeds the loss of body heat and is a major contributor to hypothermia.
- Be prepared. Make sure you have emergency provisions in your car during winter weather. Also, take along emergency equipment whenever hiking or camping in cold, damp weather, and be sure your clothing and sleeping gear are sufficiently protective for the nighttime temperatures you’ll be coping with.
- Check on those at risk. Drop by or telephone elderly relatives and friends regularly during the cold winter months to see how they are doing.
For more information
Also see Frostbite: What It Is, What to Do.