The Hormesis principle and the cold as a Eustress.

Not all stress is created equal, beware of cortisol. 

When we say ‘stress’ we usually think of life stress. Money worries, a job, relationship problems, children causing havoc. The list goes on. Chronic and persistent levels of cortisol in the bloodstream can cause serious mental and physical health problems. Tackling these usually requires fixing the cause and/or our response to the cause, which is why exercise and meditation can provide some remedy, even when we’re in the thick of it. 

Introducing ‘eustress’ (or ‘good stress’). 

When acute stress (a stress that in high doses would be dangerous) is delivered in high intensity for a short period of time e.g. a heavy resistance workout, an intense hill climb or a HIIT workout, this can be considered a good stress or a ‘eustress’. Deliberate Cold Exposure (DCE) falls into the eustress category. The cold has a unique quality that sets it apart from the other examples. Cold exposure is a stress that doesn’t trigger the release of cortisol but does increase your production of noradrenaline and adrenaline, the chemical signatures of stress. 

Hormesis = Evolution 

The principle of using eustress is to become stronger through the process of hormesis. For example, by doing 10 push-ups a day, you’ll likely work up to 20 a day by the end of the month. Maybe even 100 by the end of the year. Our bodies use the stress to adapt. As Nietzsche said, “What doesn’t kill us, makes us stronger”. Hormesis is part of our evolution. It’s based on the idea that a stressor powerful enough to kill us, applied in a short-term burst, will leave us stronger. Without us knowing, our bodies adapt, readying us for next time. As privileged and molly-coddled middle-class westerners (for the most part), we live in modern steady-state heated environments (around 22-23°c) all year round. Most likely not moving our bodies enough, not stretching enough, and breathing with a poor technique. It’s not a great picture. All this leaves the body wide open to metabolic diseases. The cold is arguably the most potent of all hormetic stressors. In a high dose it will reliably kill us, but only recently is the science now supporting its value in short-term doses, as a eustress. 

Why does the cold work as a powerful acute stressor, above all others? 

Put simply, it’s a reliable and easily measured stressor. The cold reliably triggers stress chemicals to be released. It’s why Navy SEALs and SAS training use it above heat and alongside physical training. Nobody can avoid its impact. And, it can be reliably measured through the release of norepinephrine (also referred to as noradrenaline), epinephrine (also referred to as adrenaline), as well as dopamine. In fact, noradrenaline and adrenaline are the unique chemical definition of stress and it can be easily observed in cold exposure because they are released in such high quantities – up to a five-fold increase to be exact. This happens whether the exposure is deliberate, or not. These chemicals are responsible for drive, desire, and focus. Norepinephrine acts as both a hormone and a neurotransmitter. As a neurotransmitter, it’s getting us mobilised and waking us up. As a hormone, it’s priming our metabolism for heat conservation and production. DCE co-releases norepinephrine alongside dopamine, often misunderstood as a “happy hormone”. It’s a reward for pursuit, designed to make us do it again. It makes us feel good. It’s why people may say “Cold showers are tough but I always feel great afterward, I love it!”. Collectively, this group of chemicals is called catecholamines, and literally, nothing triggers them together like cold water immersion. 

Minimal cortisol increases. 

Catecholamines are reliably released in high quantities in the cold. But what makes it more interesting is it does it with minimal cortisol increase making it such a good stressor, a eustress. Cortisol is a stress hormone designed to initiate the ‘fight or flight’ response. It increases heart rate and blood pressure (and we don’t want too much of that). Perhaps it’s nature’s signal that we’re meant to use DCE, just like we use exercise, as a regular eustress to stay healthy.

Interested to learn more about cold water exposure? Download a guide here! Or visit our journal where you will find a host of amazing cold water topics