If you have joined the growing number of people dipping into cold plunge pools for boosted immunity, you are leveraging hormetic stress for better health. Traditionally, stress has been associated with decreased health and shortened lifespan. It turns out, however, that not all stress is bad. Particularly in a societal age of technology and transportation that takes physical effort out of the equation, creating adversity is something increasingly recognized as not only beneficial but necessary for our collective well-being.

When applied in controlled doses, research shows that stress can benefit the body and mind. This concept, known as hormesis or hormetic stress, is based on the idea that small, manageable amounts of stress can trigger adaptive responses that enhance overall well-being.

Hormetic stress therapies leverage this principle to promote health, resilience, and longevity. These kinds of therapies can include physical, environmental, and mental challenges that temporarily stress the body, leading to a range of positive biological responses. This article will explore the science behind hormetic stress, its various forms, and the numerous benefits it offers.

A personal perspective

Becoming breathless with burning fatigued muscles, feeling freezing cold, or being overwhelmed with hunger – none of these are comfortable states of being. However, resting and recovering after a tough physical challenge, the tingling revitalization of a body working to re-heat itself, and eating a hearty meal to satisfy a ravenous appetite – all these countermeasures to discomfort serve to amplify the appreciation of satiety on both physical and mental/emotional levels.

While I can most relate to the enjoyment of endorphins during and after tough physical challenges, I am the first to admit that I don’t tolerate being cold very well. Even so, I had always wanted to do a Polar Bear swim to experience a tradition that so many swear by as a positive and exhilarating way to ring in a new year. My husband and I decided to try it – and living in Canada meant that nature's cold plunge would most definitely be just that! It was a blessedly mild day, but the water was like a million needles of ice that took our breath away. I only lasted 30 seconds and was prepared for a much longer time frame of feeling painfully uncomfortable. I was pleasantly surprised at how quickly I thawed; there was a visceral feeling of electrifying energy as all my blood vessels dilated to surge my body into warming back up. It was a wonderful natural high that led to feeling energized and mentally alert that lasted well into the day.

The experience shed light on something I had heard of and read briefly about – the concept of hormesis. Through the Polar Bear swim, I was introduced to the broader ways and benefits of this growing trend, and wanted to learn more.

Understanding hormesis: stress in moderation

The term "hormesis" originates from the Greek word hormē, meaning "to excite" or "to stimulate." In biological terms, hormesis refers to the phenomenon where exposure to a low dose of a potentially harmful stressor leads to adaptive and beneficial effects on the organism. These effects can be thought of as the body’s way of "tuning" its systems for greater resilience, strength, and longevity.

The key to hormesis is dose-response: at low levels, a stressor activates the body’s defense mechanisms, but at higher levels, the same stressor can become harmful. For example, while intense physical exercise or intermittent fasting can strengthen the body, excessive or prolonged exposure to these stressors can lead to injury or dysfunction. The challenge, then, is to identify the right balance where the body benefits from stress without being overwhelmed by it.

Types of hormetic stress therapies

Hormetic stress therapies come in various forms, each targeting different aspects of health. Some of the most popular and well-researched methods include:

Exercise (physical stress)

Any athlete or fitness enthusiast will be most accustomed to this type of hormetic stress. Workouts can be very uncomfortable as we push our bodies to perform or prepare for competition. Sometimes even the mental battle of deciding to lace up your shoes to go for a run can be an achievement in and of itself when you would truly much prefer to stay on the sofa.

Physical activity is one of the most well-known examples of hormetic stress. When you engage in exercise, especially intense interval or endurance-based training, you impose a stress load on the muscles, cardiovascular system, and metabolism. In response, the body adapts by becoming stronger, more efficient, and better equipped to handle future stressors. The soreness associated with the aftermath of an intense training session even becomes enjoyable for most fitness fans, but understandably serves as a major deterrent for the uninitiated. However, there are undeniable benefits to regular physical activity of which I’m sure most are known and familiar.

Key benefits include:

  • Muscle growth and repair: strength training leads to muscle microtears, stimulating muscle repair and growth during recovery.

  • Improved cardiovascular health: endurance exercise improves heart efficiency and blood vessel function.

  • Increased mitochondrial function: regular exercise enhances mitochondrial health, which boosts energy production and reduces the risk of age-related diseases.

  • Mental health: a greater sense of accomplishment, resulting in a more positive outlook and mindset. Exercise has been proven to reduce symptoms of depression and anxiety.

Cold exposure (environmental stress)

Cold exposure, such as cold showers, ice baths, or cryotherapy, is an increasingly popular hormetic therapy that involves exposing the body to cold temperatures. Cold stress triggers the body’s thermoregulation systems, activating mechanisms such as vasoconstriction (narrowing of blood vessels) and shivering to conserve heat.

While the degree and duration can of course vary, it is recommended to start with milder temperatures and shorter exposure and build tolerance. The optimal cold plunge is considered 10-15 degrees C for 3-5 minutes at a time, though experienced plungers will swear by 3-4 degrees. Further, one's body fat percentage will be a factor – those with more fat mass won't feel the cold as intensely. Beginners may want to start with 1-2 cold plunges per week, while devotees aim to plunge daily.

Key benefits include:

  • Improved circulation: alternating between cold and warm conditions can enhance blood flow, improving nutrient delivery and waste removal from tissues.

  • Enhanced immune function: regular cold exposure may boost the immune system, increasing the production of white blood cells.

  • Increased brown fat activation: brown adipose tissue (BAT) helps burn fat and generate heat, and cold exposure stimulates its activity, aiding in fat loss and weight management.

Heat exposure (environmental stress)

Just as cold exposure beneficially stresses the body, heat exposure also has its own set of advantages. Heat stress, often induced through saunas, steam rooms, or hot tubs, induces the body to sweat and work harder to cool down. This type of therapy can be especially beneficial for cardiovascular and detoxification processes.

Key benefits include:

  • Improved cardiovascular health: heat exposure can improve blood flow, reduce blood pressure, and decrease heart rate variability, contributing to overall heart health.

  • Detoxification: sweating helps eliminate toxins from the body, promoting detoxification and skin health.

  • Stress reduction: heat therapies, like saunas, have been shown to help reduce cortisol levels and promote relaxation.

Often in tandem with cold therapies, a cyclical pattern of alternating cold with heat promotes all benefits listed. The rise in global spa franchise operations, particularly of Scandinavian and Japanese varieties, reflects this popular trend.

Intermittent fasting (metabolic stress)

Intermittent fasting (IF) is another hormetic stressor that involves alternating periods of eating and fasting. This metabolic stress activates various cellular repair processes, enhances fat burning, and triggers beneficial changes in the body’s metabolism. Popular fasting protocols include the 16:8 method (fasting for 16 hours and eating during an 8-hour window) and the 24-hour OMD (one meal a day) fast. Practitioners report feelings of euphoria and mental clarity with bouts of fasting.

Most major religions have fasting occasions, representing the virtues of self-control, devotion to faith, and/or a way of purifying the body. These are typically a singular event lasting a few days or weeks at a time with the age of puberty being a common initiation age.

Key benefits include:

  • Increased autophagy: fasting promotes autophagy, the body’s process of cleaning out damaged cells and regenerating new ones, contributing to cellular health and longevity.

  • Improved insulin sensitivity: IF can help lower insulin levels and improve the body’s ability to regulate blood sugar.

  • Enhanced Fat Loss: by restricting eating windows, IF encourages the body to burn stored fat for energy.

As with other hormetic therapies, an introduction to fasting is recommended to be gradual and only appropriate for healthy individuals. Staying well hydrated is important, as is a slowed reintegration of food when breaking the fast. Likewise, planned exercise bouts should be considered with the timing of meals and associated digestion time and energy levels.

Mental stress (cognitive stress)

While physical stress is often the focus of hormesis, mental stress can also play a key role in strengthening the brain and improving cognitive function. Practices such as mindfulness meditation, controlled exposure to challenging mental tasks such as puzzles, or even cognitive-behavioral therapy (CBT) can enhance the brain’s resilience to stress and improve problem-solving and psychological well-being.

Key benefits include:

  • Neuroplasticity: mental challenges promote the growth of new neural connections, enhancing brain function and cognitive flexibility such as performing complex tasks like puzzles and crosswords.

  • Improved emotional regulation: cognitive stress training can improve the brain’s ability to regulate emotions, reducing anxiety and depression.

  • Stress tolerance: exposure to controlled mental challenges can increase the brain’s ability to handle future stressors without succumbing to burnout or overwhelm.

For those uncomfortable with silence or difficulty with focusing, research suggests that ambient instrumental music (e.g. lo-fi lounge) can serve to enhance concentration. Mindful tasks might be easier with this as a background tool.

Mechanisms behind hormetic stress

Hormetic stress works through several biological mechanisms that promote resilience and health. In summary, by creating false adversity, we allow our bodies and minds to develop grit. The ability to withstand discomfort and delay gratification is something our comfort-seeking society is often exposed to lacking. Developing grit through hormesis works through these effective biological and psychological ways:

  • Activation of stress response pathways: hormetic stress activates cellular stress response pathways, such as the Nrf2 pathway, which helps the body defend against oxidative damage, inflammation, and toxins. This process leads to enhanced antioxidant production, reduced inflammation, and improved cellular function.

  • Mitochondrial biogenesis: mitochondria, the energy-producing organelles within cells, respond to stress by increasing in number and efficiency. This is particularly important as mitochondrial dysfunction is linked to aging and numerous chronic diseases. Hormetic stress encourages mitochondrial adaptation, enhancing energy production and reducing age-related decline.

  • Gene expression: stress triggers the expression of genes involved in longevity and repair. For example, sirtuins, a group of proteins associated with longevity, are activated by various hormetic stressors, including exercise and caloric restriction. These genes promote DNA repair, reduce inflammation, and improve metabolic function.

Embracing stress for better health

While chronic and excessive stress can be detrimental to health, controlled exposure to specific stressors can trigger powerful biological responses that improve resilience, longevity, and overall well-being. Hormetic stress therapies, such as exercise, cold and heat exposure, intermittent fasting, and mental challenges, offer a promising approach to improving physical and mental health.

The key to unlocking the benefits of hormetic stress is balance: the stressor must be of appropriate intensity and duration to stimulate a beneficial response without overwhelming the body. By strategically incorporating hormetic stress therapies into your lifestyle, you can tap into the body’s remarkable ability to adapt, recover, and thrive.