A core concept of survival in just about any situation is the rule of threes. If you don’t know this rule it is that you can generally live:
- Three minutes without air
- Three hours without shelter
- Three days without water
- Three weeks without food
For this post we are going to be looking at how your body reacts when we don’t have sufficient shelter to help us regulate our body temperature and the best clothing materials to wear to help regulate your core body temperature.
The optimal environment for a human to maintain their core body temperature is between 79° and 86°F. The science of keeping your body in “the zone” of this ideal temperature is thermo-regulation. Thermo-regulation can be the difference between living and dying and is basically the practice of controlling your core body temperature.
Every year people die from power outages during heat waves or winter weather. Simple variations in environmental temperatures between 30° and 50° have wreaked havoc worldwide and many die from hypothermia or hyperthermia.
Minimal fluctuations to core temperatures can stress the human body and throw its vital systems into chaos. In the event of stress, things can get pretty ugly and actually break down at the cellular level. If your temperature suddenly plummets, the proteins in your cells clump together leaving behind areas of water that can potentially freeze and shred the delicate cell membranes.
If your body overheats, the cells can become too warm and essentially melt. Any stress at the cellular level will cause immense damage to all the body’s organs and systems needed for survival.
Hypothermia is the condition when your core temperature plummets below approximately 96° F. There are variables in the exact temperature, of course, when considering age, sex, percentage of body fat, or even time of day.
Suffering from even mild hypothermia can cause your body to burn through a ton of calories trying to keep your body and the vital organs heated, and this in turn will cut into your body’s food stores.
Your body will also limit the amount of blood flowing to your extremities making them more susceptible to damage and impairment. Shivering is another way for your body to create heat to keep you warm. While shivering, your body is creating tiny muscle contractions, thereby using energy and heating up the body. Unfortunately, shivering also burns through food stores in the process.
Hyperthermia is when your core temperature soars above approximately 100°F. Again, this can vary, but this gives you a good guideline for sustaining a healthy condition when exposed to less than ideal temperatures.
Generally, in the case of hyperthermia, your body will succumb to dehydration. Your body’s first line of defense is to circulate more than four quarts of blood per minute, dilate the blood vessels, and open the skin up to let the excess heat out.
That is why being dehydrated is so deadly. Dehydration thickens your blood making it more difficult to circulate and do its job. Your body also perspires, leaving your skin wet and cooling the outer core.
Thankfully, your body has a built-in alarm system to alert you or someone close to you that your body is stressed by either hypothermia or hyperthermia.
Stages of Hypothermia:
First signs and symptoms – Core temperature 95-96° F
- Decreased alertness
- Unable to think clearly
- Minor loss of function in fingers and toes
- Stinging pain in extremities
Simply put, you have to maintain your core temperature. People with mild hypothermia can warm themselves with additional dry layers or by stomping their feet.
Simple physical exertion is a wonderful cure when you are cold. The old saying with a wood fire is that it warms you twice. Once, when the fire is burning and another time while you are chopping and hauling the wood.
Advances signs and symptoms – Core temperature 93-94 ° F
- Uncontrollable shivering
- Lack of stability
- Increased lack of clarity
Get the affected person in doors if possible and rub cold areas. You can use the buddy system and have the warmth from one person help another person. In the Army they say that if your buddy has cold feet he should take off his socks and stick them on your belly or in your arm pits.
Serious signs and symptoms – Core temperature critical – 91-92° F
- Gray skin
- Increased lack of stability
- Speech affected
- Spasmodic shivering
For more serious signs of Hypothermia, internal heating methods should be tried. Along with external warmth, warm (not hot) fluids should be consumed also.
Mortal signs and symptoms – Core temperature 87-90 ° F
- Inability to walk
- Incoherent speech
- Shivering decreased
As with hyperthermia, if the body temperature gets this low medical help is almost always needed.
Stages of Hyperthermia
Early signs and symptoms – Core temperature between 99-100 ° F
- Lack of appetite
- Muscle spasms
- Feeling weak
- Profuse sweating
To treat mild cases of hyperthermia, we need to first remove the underlying source of the heat. If the symptoms are caused by exertion on a hot day we can treat the person with increased water consumption and rest in a cool space.
Advance signs of hyperthermia – Core temperature 101-102 ° F
- Profuse sweating
- Pale moist skin
- Possible unconsciousness
- Rapid pulse and/or breathing
- Lack of appetite
- Nausea and/or vomiting
To treat advanced hyperthermia, we can additionally use rest in a cool, shady area. Removing some articles of clothing and sponging down the head, neck and trunk area will reduce body temperature. Additional water consumption is mandatory. Immersion in a cool bath or body of water can help also.
Mortal signs and symptoms – Core temperature 103-106 ° F
- Skin hot to the touch and can be dry
- Shallow breathing
- Dilated pupils
When the body temperature is this elevated medical assistance is almost always needed, but in a survival situation this may not be possible. The body must be cooled as quickly as possible and methods such as iced IV solutions aren’t uncommon. It’s crucial we don’t get to this point so maintain close watch over your group in heat situations.
Clothing options to protect from hypothermia or hyperthermia
Wearing the proper clothing is vital so as not to inhibit, but to aid the body’s natural defenses against hypothermia and hyperthermia. Wearing the proper clothing will help you adapt to any weather situation and back to the law of threes, base your clothing around a three layer system.
Simple three layer system:
A Base layer should be wicking to keep you dry and non-restrictive when keeping you warm to allow blood to flow freely.
An Insulation layer should be next and can be removed or added as temperatures rise or fall.
The last layer is the environmental layer which should be loose fitting, water-resistant and breathable to allow moisture to flow through the fabric so it is not trapped. To test whether a fabric is water-resistant and breathable, you should put your hand on the inside and breathe onto it from the outside. If you feel the warmth of your breath, then it is water-resistant.
Remember that the layering system should be used in a hot climate as well. Some people feel that a tank top and shorts are the best clothing system, but unprotected skin only exposes your skin to the radiation of the sun. Save the skimpy clothes for the beach when you are on vacation and not in a survival situation.
Hats are another important part of clothing and give the body added protection. It is good to have a wide-brimmed, water resistant hat that will block out the sun’s rays in a warmer climate and a snug warm hat made of fleece or wool for colder temperatures to keep the heat in your head.
Clothing Fabric Choices
There are a myriad of fabrics to choose from for all the essential pieces listed. There are advantages and disadvantages to each.
Cotton and linen are best suited for hot climates. As you sweat the fabric absorbs the moisture and lays on your skin like a wet washcloth which is exactly what you want in scorching sunny conditions because it acts as an air conditioner for your skin.
Polypropylene is as unnatural as they come, but has incredible wicking capabilities and it lightweight. The downside is that if a spark from your campfire will cause the fabric to melt. It also holds the stench of sweat so well that you will never get the odor out. Not a good base layer to wear if you are trying to repopulate the world; the ladies won’t be impressed.
Wool is a natural fabric that has the ability to absorb water (up to 50% of its weight) and distribute it throughout the fabric without feeling wet. It even has the ability to keep you toasty warm even when wet, making it a natural choice in the winter where weight isn’t a factor. There are differing qualities of wool so be thoughtful in your purchase.
My mom bought a wool sweater for me as a child and I hated it because it was “itchy”. I found out later that better quality wools do not feel scratchy. The downside to wool is that it is bulky and takes longer to dry.
Polyester is completely man-made but offers the widest range of clothing choices. It can absorb a good deal of water, is somewhat water resistant, versatile.
Nylon is a super tough synthetic fabric. Most of the waterproof fabrics are made from nylon with a special coating. Try to avoid completely waterproof fabrics though, unless you are a sailor because it lacks breath-ability. Nylon dries almost instantaneously.
Down is lightweight and very warm, however it is much like cotton and will weigh you down and freeze you to death if it gets wet. It is very slow to dry.
With proper clothing layers it is possible to beat the elements and stay warm enough or cool enough to survive any situation. If you are prepping for a family, be sure to have the basic layers for every member of your family.
Also study the warning signs of hypothermia and hyperthermia because rarely does the individual suffering have the ability to recognize when they are in trouble.
The editor of Resounding Earth, and pursuer of relatively interesting information, Simon has a Masters Degree in Creative Writing and Journalism from the University of Wales, and is a photo-journalist and writer whose written and photographic work has been represented by the AFP news agency and appeared in newspapers across Europe and Asia.