The New Science of Cold Exposure: Reduce Stress, Boost Immunity & Increase Resilience with Dr Susanna Søberg #322
Dr. Susanna Søberg, a leading researcher, discusses the profound physical and mental benefits of deliberate cold and heat exposure. Her research, including the Søberg Principle, highlights how practices like cold water immersion and sauna boost brown fat, metabolism, immunity, and resilience.
Deep Dive Analysis
17 Topic Outline
Introduction to Cold Water Immersion and its Benefits
Historical Context and Societal Resistance to Cold Exposure
Understanding Brown Fat: Our Inner Heater and Metabolism Booster
The Impact of Modern Comforts on Brown Fat Levels
Cold Showers and Immune System Benefits
Hormesis: The Healthy Stress Response from Cold Exposure
Comparing Cold and Heat Exposure: Potency and Duration
Ego and Competition in Cold Immersion Practices
The Afterdrop Effect and Timing of Cold Exposure
Defining Cold Water Temperature and Relative Coldness
Introducing Children to Cold Exposure Safely
Cold Shock Response and Diving Response Explained
Mental Health Benefits: Confidence, Resilience, and Mindfulness
Neurotransmitter Release: Noradrenaline and Dopamine
Cultural Differences in Cold Tolerance and Practice
Dr. Søberg's Research Journey and the Søberg Principle
Practical Tips for Cold Exposure and Sauna Use
5 Key Concepts
Brown Fat (Healthy Brown Fat)
A special organ in the body, opposite to white fat, that acts as our internal temperature regulator. It helps metabolism by using glucose and fat from the bloodstream as fuel to generate heat, thereby increasing energy expenditure and improving insulin sensitivity. Babies have a lot of it for survival, and adults can increase its amount and efficiency through cold exposure.
Hormesis (Healthy Stress)
A process where a small, acute stressor, like cold exposure, shocks cells and prompts them to build themselves stronger and more robust. This 'micro stress' is beneficial, but overdoing it can exhaust cells and flatten or even reverse the benefits.
Cold Shock Response
The immediate physiological reaction upon entering cold water, where cold receptors in the skin send signals to the brain, releasing norepinephrine and causing blood vessels to contract. This activates the sympathetic nervous system (fight or flight response).
Diving Response
Activated when the body, particularly the head and neck, is submerged in cold water. This response activates the parasympathetic nervous system, which is the relaxing part of our nervous system, creating a unique simultaneous activation of both stress and calmness in the body.
Afterdrop
The phenomenon where the body's core temperature continues to decrease *after* exiting cold water. This occurs because warm blood from the core circulates to cold muscles and tissues, then returns to the core, causing a delayed drop in internal temperature.
8 Questions Answered
Cold exposure offers numerous physiological benefits, including increased metabolism, improved immune function, reduced insulin resistance, potential weight loss, and eased muscle/joint pain. Mentally, it boosts self-confidence, resilience, and mood, acting as a healthy stressor and a mindfulness practice.
Brown fat is a healthy type of fat, located around the spine, that regulates body temperature and boosts metabolism. It burns glucose and fat from the bloodstream to generate heat, which can help prevent obesity, type 2 diabetes, and cardiovascular diseases. Activating brown fat through cold exposure is crucial for its function and health benefits.
Humans are born with a significant amount of brown fat, but it tends to decrease with age, particularly after 40. Modern temperature-controlled environments mean we don't use this organ as much, leading to its inactivation and potential loss, contributing to increased obesity and lifestyle diseases.
Yes, a randomized controlled trial showed that ending a hot shower with 30, 60, or 90 seconds of cold water for 30 days resulted in fewer sick days from work, suggesting a boost to the immune system and overall well-being.
Water at 15 degrees Celsius and below is definitely considered cold water, based on statistics of hypothermia and accidents. However, to activate brown fat, the water only needs to be slightly colder than your skin temperature, meaning even a cool room (e.g., 19 degrees Celsius) can be effective.
It can be safe with supervision, but children have a larger surface area relative to their mass, meaning their core temperature can drop faster. It's advised for children to do quick dips rather than prolonged immersion, and they should be taught to listen to their bodies and exit when they feel too cold.
Cold exposure rapidly increases noradrenaline (up to 250% above baseline), enhancing attention and focus. It also causes a sustained release of dopamine for hours, which boosts drive, motivation, and mood without the rapid crash associated with other substances.
No, you don't need to put your head underwater to get the benefits. You can get cold adaptation and benefits even from just putting hands or feet in cold water, as the body functions as one connected system.
15 Actionable Insights
1. Activate Brown Fat Metabolism
Expose yourself to cold temperatures (e.g., cold showers, cold plunges, cooler rooms) to activate healthy brown fat, which boosts metabolism by using glucose and fat as fuel, potentially preventing obesity, type 2 diabetes, high cholesterol, and high blood pressure. Sleeping in a room at 19 degrees Celsius for a month has been shown to increase brown fat and insulin sensitivity.
2. Boost Resilience, Mood, Focus
Deliberately expose yourself to cold to increase self-confidence, resilience, and stress tolerance, as it acts as a mental workout that strengthens both mind and body. This practice immediately shifts focus from mental anxieties to physical sensations, releasing neurotransmitters like noradrenaline and dopamine that improve mood, drive, and motivation for hours.
3. 30-Second Cold Shower Immunity
Finish your warm shower with a cold blast for at least 30 seconds to potentially boost your immune system and reduce sick days, as shown in a randomized controlled trial.
4. Soberg Principle: Cold Exposure
For adapted individuals, aim for a total of 11 minutes of cold water exposure per week, divided into 2-3 days with up to three dips per session, to achieve significant health benefits. Beginners will still gain benefits from shorter exposures, even 30 seconds.
5. Optimal Sauna Use Protocol
For heat exposure, aim for 57 minutes per week in the sauna, divided into 2-3 sessions, with each session lasting between 19-29 minutes, to achieve profound health benefits including a reduced risk of mortality.
6. Progressive Cold Adaptation
Start with short durations of cold exposure (e.g., 5 seconds in a cold shower) and gradually increase the time as your body adapts, understanding that initial discomfort will lessen with consistent practice. Do not start with extreme durations.
7. Mindful Cold Exposure
Practice cold exposure mindfully, listening to your body’s signals to avoid over-stressing cells or risking hypothermia; focus on acute, micro-stress doses rather than prolonged exposure, as excessive time can flatten benefits and pose real risks. Avoid competition and be aware of the ‘after drop’ effect.
8. Vary Cold Temperature
To continuously challenge your body and mind, vary the temperature of your cold exposure, either by decreasing the temperature or slightly increasing it, rather than sticking to the same temperature once adapted. Nature provides this variation through seasons.
9. Cold for Pain Relief
Use cold exposure as a modality to reduce physical pain, as it can provide relief that lasts for the day.
10. Supervised Cold for Kids
When introducing children to cold water, ensure adult supervision and limit their exposure to quick dips, as their smaller mass and larger surface area mean they cool down faster and are at higher risk of hypothermia if they stay in too long. Teach them to listen to their body’s signals.
11. Embrace Year-Round Temperature Change
Integrate temperature changes (cold and heat) into your daily health practices year-round, as it’s a natural, healthy, and often free way to enhance overall well-being and complement other health routines.
12. Protect Head, Hands in Cold
If you find yourself getting too cold easily or experiencing discomfort in your ears or hands during cold immersion, wear a hat to retain heat and protect your ears, and keep your hands out of the water or wear gloves, as you can still reap benefits without full submersion.
13. Partial Cold Exposure Benefits
You can achieve cold adaptation and benefits even without full body or head submersion; simply exposing parts of your body, like hands or feet, to cold water can contribute to overall cold tolerance.
14. Bring a Swim Buddy
Always engage in cold water activities with a ‘swim buddy’ for safety and social support.
15. Enroll in Thermalist Course
For structured guidance on safe cold and heat exposure, consider enrolling in Dr. Soberg’s online thermalist course (soberginstitute.com), which includes breathing practices and is suitable for all experience levels, with a 10% discount using code RONGAN.
5 Key Quotes
Nature, with its simple but harsh presence, does not deceive, as opposed to the internet and social media and their endless guides and advice. Nature is sincere; it's neither for nor against us.
Dr. Susanna Søberg
The more they reject it, the more they might even need it actually.
Dr. Susanna Søberg
We have taught ourselves that the cold is not something that is useful for anything.
Dr. Susanna Søberg
It's like across society we've traded in our brown fat for white fat.
Dr. Rangan Chatterjee
I'm a cold sissy.
Dr. Susanna Søberg
3 Protocols
Immune System Boosting Cold Shower
Dr. Susanna Søberg- Take your usual hot shower.
- At the end, turn the water to cold.
- Stay in the cold water for at least 30 seconds.
The Søberg Principle (for Cold-Adapted Individuals)
Dr. Susanna Søberg- Engage in cold water immersion for a total of 11 minutes per week.
- Divide this total into 2 to 3 days per week.
- On each day, perform up to 3 dips, with each dip lasting approximately 2 to 5 minutes.
Sauna Use for Health Benefits
Dr. Susanna Søberg- Spend a total of 57 minutes per week in the sauna.
- Divide this total into 2 to 3 days per week.
- Each sauna session should be between 19 to 29 minutes.