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One of our fundamental tenets here at ReWild America is to help you become more comfortable with being uncomfortable. Your ability to tolerate discomfort directly impacts your mental and physical resiliency. Having more resiliency increases your confidence, which allows you to resist the forces that would have you safe, sedentary, and shackled to groupthink. Deliberate heat and cold exposure are great ways to make you uncomfortable and build resiliency. A more resilient citizen makes a more resilient America.

The Timeline & Evolution of Climate Control

Depending on who you ask (any Graham Hancock fans here?), at least six human species inhabited the earth one hundred thousand years ago. And seventy thousand years ago, Homo Sapiens left the heat of Africa and began to venture into colder climates.

In 1902, Willis Carrier invented the first commercial air conditioner, and in 1914, the first residential air conditioner was installed. In 1964, Cadillac released Comfort Control, the world’s first fully automatic climate control system, and by the 1970s, central air became standard in homes.

If the earliest form of climate control was 121 years ago, 121 years as a percentage of 70,000 years is 0.17%. For more than 99% of our known existence, we have been exposed to the harsh temperature fluctuations of nature. According to statistics from the Environmental Protection Agency, the average American now spends 90% of their time indoors in climate-controlled spaces.

And this is a bad thing?

Well, yes and no. But before you stop reading because you think I’m advocating for removing your heating and cooling system, I am not.

The human body is adapted to respond and adjust to a wide range of environmental conditions, and these adaptive responses can play significant roles in our physiological and psychological health. The potential impacts of sitting inside on a hot summer day, skipping the chance to immerse yourself in some frigid water, and having zero exposure to thermal stress may be impacting our health.

Lack of Thermal Stress: Potential Impacts

1. Reduced Thermoregulatory Efficiency: Constant exposure to uniform, comfortable temperatures may impair the body's thermoregulatory capacity. Our bodies are designed to adapt to temperature variations, and this adaptation process can strengthen our ability to regulate body temperature, potentially making us more resilient to heat and cold stresses.

2. Impaired Metabolic Function: Exposure to cold has been shown to stimulate brown adipose tissue (BAT), enhancing calorie burning and playing a role in body weight regulation and metabolic health. Living in constantly warm environments may limit these metabolic adaptations, potentially contributing to metabolic syndrome and obesity.

3. Decreased Cardiovascular Stress Adaptation: Both heat and cold exposure can improve cardiovascular function through different mechanisms. Cold exposure can improve circulation and reduce inflammation, while heat exposure (such as sauna use) can increase cardiac output and improve vascular function. Avoiding thermal stress may result in missed opportunities for these cardiovascular benefits.

4. Diminished Immune Response: Some research suggests that regular exposure to mild stressors, including thermal stress, can enhance the immune system's function. For example, cold exposure has been linked to increased levels of specific white blood cells and inflammatory mediators, potentially offering some protection against infection.

5. Mental Health and Mood: Evidence suggests that exposure to cold can positively affect mood and mental health, possibly by releasing endorphins. Similarly, the use of heat stress, such as sauna bathing, has been associated with reduced risk of depression and anxiety. The lack of these natural stressors could potentially impact mental health negatively.

The Need for Environmental Variability

Environmental variability is crucial in understanding the potential health impacts of spending too much time in climate-controlled settings. Just as the body benefits from physical exercise by adapting to stress, it also benefits from environmental "exercise" through exposure to varying temperatures. This exposure can activate adaptive pathways that contribute to improved health and resilience.

The easiest way to incorporate thermal stress into your life is to have a sauna and cold plunge in your home or local gym, but not everyone has that option. Below are some options for people who don’t have access to saunas and cold tubs.

Ways to Incorporate Thermal Stress in Your Life

Cold Exposure

• Cold Showers: Start or end your shower with a minute or two of cold water. Gradually increase the time spent in cold water to improve tolerance and resilience. This works better in the winter when the water is frigid.

• Outdoor Exposure: In cold weather, spend time outside in light clothing to expose your body to the cold. This can be as simple as taking a walk or performing outdoor activities. Try shoveling snow in your T-shirt or getting the mail in your skivvies during a blizzard.

• Ice Baths: Head to your local gas station and pick up a few bags of ice. Fill up your bathtub with cold water, add the ice, and have yourself a poor man’s cold plunge. Try to stay in it for 3-5 minutes – it probably won’t be as cold as a purpose-built cold tub.

• Frigid Bodies of Water: This can be dangerous if you don’t know what you’re doing, but getting in the ocean, a lake, or stream in the winter is one of the best ways to get cold exposure. Seriously, be careful and have someone watching you who is capable. I shoot for at least 2-3 minutes, but you can start with a quick dip and build up from there.

Heat Exposure (I know what you’re thinking, and I believe you should do both)

• Hot Baths: A hot bath can simulate some of the effects of a sauna, including increased heart rate and sweating. Adjust the water temperature to where you’re uncomfortable, but your skin isn’t peeling off, and aim for a duration that challenges you.

• Sweat Lodge: If you have saplings, string, a tarp or blanket, and a place to make a fire and heat up rocks, you can create a sweat lodge. Depending on how well you build it, it will be very similar to a sauna.

• Hot Yoga: Participating in hot yoga classes or practicing yoga in a hot room can increase body temperature and induce sweating, offering a form of heat stress. You can also blast a space heater in your living room and follow along with a yoga app like Down Dog.

• Layered Clothing During Exercise: Wearing extra layers of clothing during exercise, especially in a warm environment, can increase body temperature and sweating, simulating a mild heat stress effect. This is particularly miserable, and you probably won’t do it unless you’re on a high school wrestling team.

Final Thoughts

A common approach to incorporating heat and cold exposure into a weekly training routine involves engaging in each three to four times a week, allocating 20 minutes for heat exposure and 2-3 minutes for cold exposure. However, don’t become overly fixated on these specific durations, particularly when adapting to circumstances or seeking natural opportunities. While I don't intend to plunge into an icy lake three times a week, I seize the opportunities when they arise, understanding the significant health benefits of additional thermal stress. Beyond the health advantages, this practice also enhances mental toughness and resilience. I firmly believe in doing things that make you uncomfortable to keep your edge sharp. Don’t go quietly into the night as they say.

Precautions & Disclaimer: You and only you are responsible for your safety! Rapid immersion into cold water may cause dangerous changes in the breath and heart rate, known as the cold shock response, which can be dangerous and even fatal. Likewise, over-exertion in a hot environment can cause heat stroke, which can also be deadly. With cold and heat exposure, starting off gradually and building your tolerance over time is essential.

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