Cold plunging makes you happy—and much more. Why? Because many hormonal processes take place in your body when you immerse yourself in cold water. Your body reacts to this extreme situation with a mix of hormones released at once.
In modern society, we rarely face such extreme conditions, so these natural processes are often forgotten. Yet the controlled release of hormones through cold plunging is one of the best things you can do for yourself and your health.
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What Are Hormones?
Hormones are chemical messengers produced by certain cells and glands in the body. They travel through the bloodstream, bind to receptors, and influence cell function.
They play a decisive role in many essential processes, such as:
- metabolism
- organ function
- reaction to stress and anxiety
- mood and sleep cycles
Key Hormones in the Human Body?
Here are some of the most important hormones influencing the body. Many of them are also triggered during a cold plunge:
- Insulin: Regulates blood sugar levels by transporting glucose from the blood into cells.
- Oestrogen & Testosterone: Sex hormones that regulate sexual characteristics and reproductive function.
- Adrenaline & Noradrenaline: Stress/ danger hormones responsible for the “fight or flight” response.
- Thyroxine: A thyroid hormone that regulates the metabolism, growth, and development of your body.
- Cortisol: The “stress hormone”, influencing metabolism and immune function.
- Melatonin: Regulates the body’s sleep-wake rhythm.
- Growth hormones: Support growth and development during childhood.
- Serotonin: Regulates mood, appetite, and sleep.
What Happens When the Hormone Balance Is Disturbed?
A disrupted hormone balance can affect many systems in the body, leading to conditions such as:
- Diabetes
- Thyroid diseases
- Hormone disorders
- Cancer
- Obesity
- Depression
- Infertility
- Acne and skin issues
- Chronic tiredness
The Fight-or-Flight Reflex and Cold Plunging
In our daily lives, the fight-or-flight reflex is rarely triggered. Yet when you expose your body to extreme cold, this ancient survival mechanism is reactivated.
The cold plunge is perceived as stress. Your body reacts by releasing a cocktail of hormones that prepare and protect you in this potentially life-threatening situation. Evolutionarily, this response helped humans survive threats from nature, predators, and disease.
Today, many people experience constant low-level stress instead. Unlike fight-or-flight, this chronic stress does not healthily release hormones. Cold water immersion offers a safe, controlled way to activate and then resolve this stress response, restoring balance.
Which Hormones Are Released During A Cold Plunge?
Hormones released during cold plunging include testosterone, adrenaline and noradrenaline, endorphins, cortisol, thyroxine, and leptin.
Testosterone
The male sex hormone testosterone is released to a greater extent during cold plunging. Some studies have shown that cold increases testosterone production. For example, men who have completed a session in a cold chamber have higher testosterone levels than a comparable group of men who were in a normal temperature environment. It is believed that the cold reduces the activity of enzymes that break down testosterone, thereby increasing testosterone levels.
Adrenaline & Noradrenaline
Adrenaline and noradrenaline are stress hormones produced by the adrenal glands. They are released in stressful situations to prepare the body for strenuous physical activity.
These hormones:
- Increase the heart rate and blood pressure during cold plunging to supply more oxygen and nutrients to the muscles.
- Constrict blood vessels in the extremities to conserve energy for vital organs in the center of the body.
- Are used as neurotransmitters in the brain and stimulate the central nervous system. This increases your mental alertness and attention.
- Dilate pupils to improve vision
This explains the heightened awareness and energy that lasts long after a cold plunge.
Cortisol
Cortisol is a hormone that is produced in the adrenal cortex and plays an important role in the body’s metabolism and stress response.
Cortisol regulates blood sugar levels and the metabolism of fats, proteins, and carbohydrates. During cold plunging, cortisol increases blood sugar levels to provide the body with more energy.
It also has an anti-inflammatory effect, which may explain why many cold plungers report fewer illnesses.
Endorphins
Endorphins are endogenous opioids produced by the hypothalamus that act as natural painkillers and mood enhancers. In response to the cold and the associated pain, endorphins are released to calm the body and relieve the pain.
Cold water plunging can cause a range of physical discomforts, such as headaches, nausea, muscle cramps, and breathing difficulties. Endorphins help to alleviate these symptoms by reducing pain and discomfort and creating a feeling of relaxation and well-being.
Endorphins also have a positive effect on mood and can increase feelings of happiness and contentment. This helps to mentally prepare the body for the cold and reduce your stress levels.
Endorphins normally only have a short-term effect that lasts for a few minutes. Once released, they are broken down and excreted relatively quickly in the body. However, the release of endorphins through certain activities or events, such as intense physical exertion, stress, or positive experiences such as cold plunges, can also have longer-lasting effects. Anyone who has tried a cold plunge will be able to confirm this euphoric feeling even hours after exposure to the cold.
Thyroxine
Produced by the thyroid gland, thyroxine regulates metabolism.
Increased physical exertion, as occurs during cold water swimming, speeds up the metabolism and increases energy requirements. Cold water exposure stimulates thyroxine production, speeding up energy use and fat burning.
Leptin
Produced in the body’s fat cells, Leptin helps regulate appetite and metabolism. Cold plunging can lower appetite, boost metabolism, and encourage the formation of brown fat, which burns more energy even after the plunge.
Melatonin
Melatonin regulates the sleep-wake cycle. It is normally produced in larger quantities in the dark and signals to the body that it is time to rest and fall asleep. You should therefore also avoid so-called blue light so as not to prevent or interrupt melatonin production in the evening.
Studies on cold exposure to melatonin production in rats found that exposure to cold leads to increased production of melatonin. Another study from 2017 on humans found that cold water immersion before bedtime led to an increased concentration of melatonin in the blood. This suggests that cold plunging can also help you fall asleep better as it increases melatonin production.
Dopamine
This neurotransmitter regulates motivation, reward, and movement. Studies suggest cold exposure increases dopamine activity in the brain, activating the reward center and improving mood.
Why Cold Plunging Makes You Happy
The combined release of endorphins, dopamine, and other hormones creates a powerful natural high. Many cold plungers report feeling energized, focused, and deeply content for hours afterward.
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