How to Use Cold & Heat Exposure to Improve Your Health | Dr. Susanna Søberg

Introduction

In this section, Andrew Huberman introduces the podcast and his guest, Dr. Susanna Sörgel. He provides a brief overview of her research on deliberate cold and heat exposure and how it can be used to enhance human metabolism.

Introducing Dr. Susanna Sörgel

• Dr. Susanna Sörgel is introduced as a guest on the podcast.

• Her research focuses on how deliberate cold exposure and deliberate heat exposure can be used to enhance human metabolism.

• She is the first author of a seminal study which discovered the minimum thresholds for deliberate heat and deliberate cold exposure for increasing Brown fat thermogenesis.

• Today's discussion with Dr. Sörgel focuses on the role of deliberate heat and deliberate cold exposure on metabolism.

Effects of Cold and Heat Exposure

In this section, Andrew Huberman discusses with Dr. Susanna Sörgel about the effects of cold and heat exposure on neurotransmitter production, namely dopamine, epinephrine, and norepinephrine.

Deliberate Cold and Heat Exposure

• The discussion includes common questions about deliberate cold and deliberate heat exposure.

• The difference between cold showers versus cold immersion up to the neck versus total body cold immersion is discussed.

• Going back and forth between heat and cold changes fundamentally the way that heat and cold impact metabolism hormones, neurotransmitter production are discussed in detail.

Winter Swimming Book Review

In this section, Andrew Huberman reviews Dr. Susanna Sörgel's book, "Winter Swimming," which breaks down the different aspects of deliberate heat and deliberate cold into its various constituent parts.

Winter Swimming Book

• Dr. Sörgel is the author of a recent book entitled "Winter Swimming."

• The book breaks down chapter by chapter the different aspects of deliberate heat and deliberate cold into its various constituent parts.

• It's a very thorough read and an easy and accessible read that will allow you to embrace those protocols with the greatest degree of confidence that you're going to obtain the specific endpoints that you're interested in and to do so safely.

Podcast Disclaimer

In this section, Andrew Huberman emphasizes that this podcast is separate from his teaching and research roles at Stanford. He also thanks the sponsors of today's podcast.

Podcast Disclaimer

• This podcast is separate from Andrew Huberman's teaching and research roles at Stanford.

• The sponsors of today's podcast are thanked, including Plunge, which makes what he believes is the most versatile at-home self-cooling cold plunge for deliberate cold exposure.

The Benefits of Cold Plunges

In this section, the speaker talks about the benefits of cold plunges and how they can be easily accessed at home.

Benefits of Cold Plunges

• Deliberate cold exposure is easy to get at home with a cold plunge.

• The plunge is easy to keep clean, which is essential for preventing bacteria growth.

• Maui Nui venison offers nutrient-dense products that are sustainable and delicious.

• Thesis designs custom nootropics to help you achieve specific mental or physical states.

Introduction to Dr. Susanna Soberg

In this section, the speaker introduces Dr. Susanna Soberg and explains how they got connected.

Introduction to Dr. Susanna Soberg

• Dr. Susanna Soberg is introduced as a guest on the podcast.

• The speaker explains their interest in cold thermogenesis and physiology.

Understanding Traumatic Brain Injury (TBI)

In this section, Dr. Susanna Soberg discusses traumatic brain injury (TBI), its causes, symptoms, and treatments.

Understanding TBI

• TBI occurs when there is an external force that causes damage to the brain.

• Symptoms of TBI include headaches, dizziness, nausea, confusion, memory loss, and more.

• TBI can be caused by a variety of factors, including sports injuries, car accidents, and falls.

• Treatment for TBI includes rest, medication, physical therapy, and cognitive rehabilitation.

Cognitive Rehabilitation for TBI

In this section, Dr. Susanna Soberg discusses cognitive rehabilitation as a treatment option for TBI.

Cognitive Rehabilitation

• Cognitive rehabilitation is a type of therapy that helps individuals with brain injuries improve their cognitive function.

• The goal of cognitive rehabilitation is to help individuals regain their independence and improve their quality of life.

• Cognitive rehabilitation can include various techniques such as memory training, problem-solving exercises, and more.

• The effectiveness of cognitive rehabilitation depends on the severity of the injury and the individual's willingness to participate in therapy.

Virtual Reality Therapy for TBI

In this section, Dr. Susanna Soberg discusses virtual reality therapy as a treatment option for TBI.

Virtual Reality Therapy

• Virtual reality therapy is a type of treatment that uses immersive technology to simulate real-life situations.

• Virtual reality therapy can be used to treat various conditions such as anxiety disorders and PTSD.

• For individuals with TBI, virtual reality therapy can help improve balance and coordination skills.

• Virtual reality therapy has been shown to be effective in improving cognitive function and quality of life for individuals with TBI.

The Importance of Sleep for Brain Health

In this section, Dr. Susanna Soberg discusses the importance of sleep for brain health and recovery.

Importance of Sleep

• Sleep is essential for brain health and recovery.

• During sleep, the brain consolidates memories and processes information.

• Lack of sleep can lead to cognitive impairment, mood disorders, and other health problems.

• Getting enough high-quality sleep is crucial for overall health and well-being.

Tips for Improving Sleep Quality

In this section, Dr. Susanna Soberg provides tips for improving sleep quality.

Tips for Better Sleep

• Stick to a regular sleep schedule.

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Introduction

In this section, the host introduces the guest and thanks him for his work in bringing quality information about cold exposure to a wider audience. The guest is an author who has written a book on the science and impact of deliberate cold exposure and sauna.

Thanking the Guest

• The host thanks the guest for being there.

• The host appreciates the work that the guest has done in bringing quality information about cold exposure to a wider audience.

Physiology of Cold Exposure

In this section, the guest explains what happens in our physiology when we get cold. He talks about how neurotransmitters are activated in our body when we experience cold stressors.

Effects of Cold Exposure on Neurotransmitters

• Cold exposure activates neurotransmitters such as catecholamines.

• If you are very hot before getting into cold water, it will feel less stressful.

• The temperature difference from your skin to the cold is going to give you a shock.

• Going outside in the cold wind also activates your sympathetic nervous system.

Sympathetic Nervous System

• The sympathetic nervous system creates accelerations in heart rate and feelings of alertness.

• It's accompanied by stress but also waking up in the morning.

Deliberate Cold Exposure Protocol

In this section, the host asks questions related to deliberate cold exposure protocol. They discuss how to gauge what is best for approaching deliberate cold exposure protocol and how discomfort can be balanced with time spent in it.

Approaching Deliberate Cold Exposure Protocol

• It's hard to give a straight prescription for how cold water should be because it depends on current temperature and surface skin temperature.

• Getting into more uncomfortable colder water feels more stressful if already feeling chilly.

Balancing Discomfort with Time Spent

• Spending more time in the cold will get us the same benefit as getting into very uncomfortably cold water for a short period of time.

• The discomfort level should be balanced with the amount of time spent in it.

Cold Exposure and Resilience

In this section, the speaker discusses how to build resilience through cold exposure. He explains that getting uncomfortable in the cold is necessary to activate the sympathetic nervous system and catecholamines. The speaker also talks about the "cold shock" response and how it can be controlled through adaptation.

Building Resilience Through Cold Exposure

• Training in cold exposure can help you get adapted to it.

• Building up your adaptation will make the "cold shock" subside.

• Cold water immersion should not be comfortable; it should be hard.

• Deliberate cold exposure is all or none, making it difficult to titrate and adjust levels.

Varying Responses to Cold Exposure

• People vary tremendously in their ability to embrace discomfort from cold exposure.

• Some people feel better in the cold while others dread it more.

• People who avoid the cold feel more pain when exposed to it.

Differences in Impact of Cold Exposure

In this section, the speaker discusses differences in impact between being outside in a t-shirt, taking a shower, and immersing oneself up to the neck.

Impact of Different Types of Cold Exposure

• Being outside in a t-shirt has less impact than taking a shower or immersing oneself up to the neck.

• Immersing oneself up to the neck has the most impact.

Cold Exposure and Brown Fat Activation

In this section, the speaker discusses how cold exposure can activate brown fat in the body, which can increase metabolism. The more skin exposed to cold, the more potent the activation of cold receptors in the skin.

Cold Water Immersion vs. Cold Wind Exposure

• Covering your body in cold water activates all your cold receptors in the skin and rapidly activates your sympathetic nervous system.

• Going out in a t-shirt in the cold wind will also activate your sympathetic nervous system but to a lesser extent.

Brown Fat Activation

• Cold exposure on the skin immediately activates brown fat, which is temperature regulating tissue that increases metabolism.

• Muscles are another tissue that can increase thermogenesis and shiver to increase body temperature.

Cold Showers

• There are fewer studies on cold showers than on cold immersion because it's harder to control for variables such as clothing and vulnerability.

• Taking a cold shower could activate brown fat and increase metabolism, but there is not enough research yet to confirm this.

Pathway from Skin Receptors to Brown Fat Activation

In this section, the speaker discusses how brown fat is activated by cold exposure on the skin and explains what we know about the pathway from skin receptors to brown fat activation.

Activating Brown Fat through Cold Exposure

• Any form of cold that people register as uncomfortable or jarring activates brown fat.

Pathway from Skin Receptors to Brown Fat Activation

• The pathway from skin receptors to brown fat activation is not fully understood yet.

Activation of Brown Fat

In this section, the speaker discusses how cold water immersion leads to an increase in neurotransmitters in the brain, which activates brown fat. The activation of brown fat is triggered by three parallel pathways: cold skin, cold receptors in the skin directly to brown fat, and shivering muscles.

Activation of Brown Fat

• Cold water immersion leads to a rapid increase in neurotransmitters in the brain.

• Three parallel pathways activate brown fat: cold skin, cold receptors in the skin directly to brown fat, and shivering muscles.

• Brown fat is activated when we get warmer on our skin and may be a temperature regulator in our body.

• Shivering increases metabolism and burns calories. It is important as long as you don't get too hypothermic.

Importance of Shivering

In this section, the speaker explains that shivering is good because it increases metabolism and burns calories. The after drop phenomenon occurs when core temperature decreases even after getting out of cold water due to blood vessels opening again and warm blood flowing out.

Importance of Shivering

• Shivering increases metabolism and burns calories.

• After drop phenomenon occurs when core temperature decreases even after getting out of cold water due to blood vessels opening again and warm blood flowing out.

The Importance of Cold Exposure

In this section, the speaker discusses the importance of ending on cold and not avoiding shivering as it is a way to train your body.

Shivering as Training

• Shivering is a way for your body to train itself.

• It trains your muscles, metabolism, and increases insulin sensitivity.

• Exposing muscle cells or brown fat cells to healthy stresses like exercise, cold exposure, and heat exposure makes them better at activating and trading.

• This process creates healthy stress called homiesis in the cells.

• The more you expose your cells to these kinds of stresses, the more robust they become.

Parallels with Exercise

• Shivering is similar to exercising in that it causes discomfort but leads to long-term benefits.

• Exercise causes high blood pressure, stress hormones, and inflammation markers during activity but sets in motion adaptations that allow for lower levels at rest.

• Similarly, cold exposure sets in motion long-term changes that improve health.

Long-Term Changes from Cold Exposure

• Deliberate cold exposure leads to long-lasting increases in catecholamines dopamine norepinephrine and epinephrine for many hours after exposure.

• Other changes include activation of brown fat and improved metabolism.

Fitness Adaptations of Deliberate Cold Exposure in the 1950s

In this section, the speaker discusses how deliberate cold exposure can lead to fitness adaptations that improve one's ability to handle cold water and prevent lifestyle diseases.

Fitness Adaptations of Deliberate Cold Exposure

• With repeated exposure to cold water, the body adapts and becomes more comfortable in the cold.

• The body builds brown fat, which is more efficient at heating up the body and improving insulin sensitivity.

• Capillaries in the skin become better at constricting, providing a better shield for the body against future exposure to cold water.

• Stress response decreases over time with repeated exposure to cold water.

• Activation of brown fat or muscles leads to an increase in metabolism, which improves insulin sensitivity and glucose balance.

Benefits of Deliberate Cold Exposure on Insulin Sensitivity

In this section, the speaker discusses how deliberate cold exposure can improve insulin sensitivity and prevent lifestyle diseases.

Study on Winter Swimming Season

• A study conducted on middle-aged men and women during one winter swimming season showed lower blood pressure, lower heart rate, and better insulin sensitivity after four or five months of winter swimming.

• Long-term outcomes could include lower blood pressure, better insulin sensitivity, better glucose balance, and less inflammation in the body.

Athletic Greens Sponsorship

In this section, the speaker acknowledges Athletic Greens as a sponsor for their podcast.

Athletic Greens Benefits

• Athletic Greens provides probiotics for gut health, which is important for overall health.

• Athletic Greens contains adaptogens, vitamins, and minerals to meet foundational nutritional needs.

• Athletic Greens offers five free travel packs and a year's supply of vitamin D3 K2.

The speaker takes a break from discussing deliberate cold exposure in this section.

Importance of Blood Pressure

In this section, the speaker discusses the importance of blood pressure and how it is often overlooked in discussions about health optimization.

Blood Pressure and Health

• Cerebral vascular disease and cardiovascular disease are the top two reasons for death worldwide.

• Not smoking or vaping, monitoring blood markers like apob, and controlling blood pressure are key factors in addressing these diseases.

• Despite its importance, blood pressure is often overlooked in discussions about health optimization.

Brown Fat Biology

In this section, the speaker discusses brown fat biology and its potential to help control blood pressure.

Characteristics of Brown Fat

• Brown fat is located in specific areas of the body but can be more widespread than previously thought.

• It is rich in mitochondria and can grow or decrease depending on adrenaline levels.

• While it can activate metabolism, chronically high adrenaline levels can lead to high blood pressure and weight loss.

Activating Brown Fat

• The goal is not to increase brown fat but rather to keep it activated.

• Cold exposure is one way to activate brown fat and potentially help control blood pressure when combined with other forms of exercise.

Brown Fat and Insulin Sensitivity

In this section, the speaker discusses brown fat as an insulin-sensitive organ in our body. The speaker explains that just like muscles, brown fat can become less sensitive to insulin, which could be one of the reasons why we don't see much brown fat in elderly people.

Brown Fat and Insulin Sensitivity

• Brown fat is an insulin-sensitive organ in our body.

• As we get obese, just like muscles get less sensitive to insulin, brown fat does as well.

• This decrease in sensitivity could be a reason why we don't see much brown fat in elderly people.

Physical Work and Insulin Sensitivity

In this section, the speaker talks about studies showing that people who work outside doing physical labor have more brown fat. The speaker also clarifies that insulin sensitivity is a good thing and is associated with obesity.

Physical Work and Insulin Sensitivity

• Studies show that people who work outside doing physical labor have more brown fat.

• Insulin sensitivity is a good thing; you want your cells to be sensitive to insulin.

• Insulin insensitivity is type 2 diabetes and is associated with obesity.

Muscleskeletal System Workouts

In this section, the speaker shares their experience of working out at home but going to the gym once or twice a week. They talk about individuals at the gym who are incredibly lean despite not being particularly large or muscular. The speaker also talks about how these individuals grew up doing manual labor or were postmen/women.

Muscleskeletal System Workouts

• The speaker usually works out at home but goes to the gym once or twice a week.

• There are individuals at the gym who are incredibly lean despite not being particularly large or muscular.

• These individuals grew up doing manual labor or were postmen/women.

Hormone Augmentation and Physical Labor

In this section, the speaker talks about how they can spot hormone augmentation and how it's not the reason why some people are fit. They also talk about how people who have done physical labor their whole life tend to look different from those who haven't.

Hormone Augmentation and Physical Labor

• The speaker can spot hormone augmentation but that's not why some people are fit.

• People who have done physical labor their whole life tend to look different from those who haven't.

Brown Fat Activation

In this section, the speaker talks about how brown fat can be activated with just a little bit of exposure to cold. They also discuss non-exercise induced thermogenesis (NEAT) and whether just staying active is enough to activate brown fat.

Brown Fat Activation

• Cold is the most potent stressor activator of our brown fat because it's our temperature regulating organ in our body.

• Studies show that if you put your hand in cold water, you can activate your brown fat just by getting a temperature change on your skin.

• Going outside in a t-shirt or wearing cooling vests for 10 days will grow your brown fat.

• It's unclear whether just staying active is enough to activate brown fat or if there needs to be a deliberate cold exposure.

Activating Brown Fat

In this section, the speaker discusses how to activate brown fat and its benefits.

Sleeping in a Cold Room

• Studies have shown that sleeping in a room at 19 degrees Celsius can activate brown fat.

• A group of subjects who slept in a room at 24 degrees Celsius for a month had decreased insulin sensitivity compared to those who slept at 19 degrees Celsius.

• Sleeping in a warm room (27 degrees Celsius) resulted in even less activation of brown fat and insulin sensitivity.

Exposing Yourself to Cold

• Exposing yourself to cold temperatures can activate brown fat because it is sensitive to adrenaline.

• Brown fat can decrease unhealthy white fat by taking up glucose and fatty acids from the bloodstream.

• Exposure to cold temperatures can be achieved through various methods such as sleeping in a cold room, taking cold showers, or going outside in the cold.

Activation of Brown Fat

• The speaker conducted an experiment where she measured blood pressure and heart rate during exposure to cold water.

• Activation of brown fat occurs when co-receptors on the face are exposed to cold temperatures.

• Brown fat is located centrally around the central nervous system and under the clavicular bones. It is close enough to the skin surface that it can be measured with an infrared thermography camera.

Cold Adaptation and Brown Fat

In this section, the speaker talks about his experience working in a lab that studied thermogenesis in animals. He shares how he adapted to the cold environment and activated his brown fat.

Cold Adaptation

• The speaker was initially uncomfortable in a cold room but was advised by Dr. Carlisle to wear a t-shirt for two or three days to adapt to the cold.

• Dr. Carlisle explained that getting uncomfortably cold can activate brown fat, which expands or adds mitochondria, making one more comfortable in a cold environment.

• The speaker got leaner during this time and noticed a powerful effect on his thermal regulation system.

Brown Fat Activation

• Activating brown fat through exposure to cold environments can lead to increased calorie burn.

• There is a saying in Scandinavia that advises wearing fewer layers before winter and more layers before summer to prepare for the respective temperatures and activate brown fat.

Historical Context

• In Scandinavia and Russia, babies were put outside to sleep in the cold as early as the 1950s as part of an effort to increase resilience to the cold and boost immune systems. This practice continues today in Denmark.

Danish Culture and Fitness

In this section, the speaker talks about his admiration for Danish culture and how he noticed that people in Copenhagen are much fitter than those in the United States.

Fitness in Copenhagen

• The water in the harbor was cold even though it was summertime.

• People in Copenhagen are dramatically fitter than those in the United States. Everyone is bicycling everywhere, and not many people wear sunglasses to extract as much photon energy from the sun as possible.

• Swimmers were swimming in cold water like it was nothing, and their age range was remarkable. There were young kids, triathlete-looking types, and even people in their 70s or 80s.

Inside Tracker Sponsorship

In this section, the speaker talks about a sponsor called Inside Tracker that offers personalized nutrition platforms to help individuals better understand their bodies.

Inside Tracker Sponsorship

• Inside Tracker is a personalized nutrition platform that analyzes data from blood and DNA to help individuals reach their health goals.

• The ultimate plan now includes three new hormone markers critical to measure during a woman's reproductive and menopausal years - estradiol, progesterone, and thyroid-stimulating hormone.

• To try Inside Tracker, go to insidetracker.com/huberman to get 20% off any of its plans.

Brown Fat Study

In this section, the speaker discusses his study on brown fat and metabolism using cold exposure and sauna.

Brown Fat Study

• The study explored not just cold but also sauna and the co-use of cold and sauna as a way to probe metabolism and brown fat.

• Doing human studies is different from doing knockout studies because people are different even in groups. When the speaker started this research in 2016, he did not know what brown fat was, so he started reading up on it.

• The study involved measuring various markers related to metabolism and brown fat in participants who underwent cold exposure and sauna sessions.

Brown Fat Activation Study

In this section, the speaker discusses her research on brown fat activation and how she came up with the idea of studying winter swimming as a way to activate brown fat.

Researching Brown Fat Activation

• The speaker read up on research about brown fat activation and found a paper about sleeping in the cold to be fascinating.

• She wanted to find an activity that could activate brown fat and involve movement. The idea of winter swimming came up, but there was little literature on its effectiveness.

Proof of Concept Study

• A proof of concept study was conducted with a small number of participants to see if there were any differences between groups before and after winter swimming.

• The main outcome measured was PET scans of brown fat, but other mechanisms were also studied such as taking fat biopsies from white fat.

Personal Experience with Winter Swimming

• The speaker was not a winter swimmer when she started the study and was initially uncomfortable with the cold water. However, she eventually tried it out herself after being encouraged by winter swimmers under Jetty.

• She found that while it was painful at first, she eventually became more comfortable with it and began incorporating it into her routine for its potential health benefits.

Benefits of Cold Water Immersion

In this section, the speaker discusses their personal experience with cold water immersion and the benefits they have observed.

Personal Experience with Cold Water Immersion

• The speaker has learned to control the gasp reflex and hyperventilation associated with cold water immersion.

• Although uncomfortable during the activity, the speaker loves how they feel after getting out of the cold water.

• Blood pressure and heart rate can increase in those who are new to this kind of activity, causing anxiety. However, after getting out of the water, the speaker feels fantastic and invigorated.

• The speaker observes that one dip is enough to get energy and a positive feeling. They do it once or twice a week.

Study on Cold Water Immersion

• The study aimed to observe winter swimmers who were already adapted to cold water immersion and compare them to a matched control group based on diet.

• The study was designed as a proof of concept for ethical approval before conducting an intervention study.

Women and Men's Thermal Comfort

In this section, the speaker discusses the differences in thermal comfort between men and women.

Physiological Differences

• Women have a lower peripheral temperature than men, especially on hands and ears.

• Men have bigger hearts than women, which allows them to pump out more blood peripherally. This could explain why men tend to have warmer hands.

• Men are more comfortable at 22 degrees Celsius while women are thermal comfortable at 24 degrees Celsius.

Study Design

• The study focused on one gender (men), to eliminate confounding factors that could impact results.

• Winter swimmers were recruited for the study because they already adapted to cold water but did not stay too long in it.

• Winter swimmers stayed in the water for only one to two minutes, which activates their rest and digest system or parasympathetic nervous system.

Diving Response

• Submerging into cold water activates the diving response, which slows down heart rate and oxygen consumption in the body.

• Putting our face into cold water or going underwater activates a calming relaxation response through the parasympathetic nervous system.

The Diving Reflex and Calming Response

In this section, the speaker discusses the diving reflex and calming response that are activated when submerging into cool water.

Activation of Diving Reflex

• The diving reflex is activated when you submerge into cool water, even just to the neck.

• You don't have to do it with your face as far as I understand.

• When you activate your diving response, you will slow down your oxygen consumption in your body.

Importance of Survival System

• The body tries to preserve oxygen so that you will not get hypothermic too fast.

• This survival system is important for us because it activates both the sympathetic and parasympathetic nervous systems.

Mental Benefits

• Activation of the diving response can also activate serotonin in your brain which is good for mental balance.

• People often report feeling good after winter swimming due to these mental benefits. Studies are needed on this topic.

Winter Swimming Study Design

In this section, the speaker describes a study design involving winter swimmers.

Study Participants

• Winter swimmers who had been doing this for a few seasons were recruited as subjects for the study.

Cold Water Exposure Protocol

• Participants got into cold water up to their neck by climbing down a ladder or jumping in three times per day, two to three times per week.

• Each time they went in, they stayed there for one to two minutes before getting out and getting into a sauna.

• They took three rounds of dips and two sauna sessions each day they went, starting in the cold and ending in the cold water.

Sauna Temperature and Duration

• The temperature of the sauna was about 80 degrees Celsius, and participants stayed there for 10 to 15 minutes depending on how many times per week they went.

Water Temperature

• The water temperature varied from around 15 degrees Celsius down to an average of two to four degrees Celsius when it was the coldest.

Importance of Ending on Cold

In this section, the speaker explains why it is important to end on cold.

Sober Principle

• It is important to end on cold due to the sober principle.

Benefits of Cold Exposure

• Cold exposure has been shown to have numerous health benefits such as reducing inflammation, improving circulation, and boosting immunity.

Nature's Impact on Health

• Doing winter swimming outdoors in nature can also lower stress levels and have a positive impact on mental health.

Importance of Timing for Brown Fat Activation

In this section, the speaker emphasizes the importance of timing when it comes to activating brown fat. They explain that people should try to activate their brown fat during the daytime and find out what works best for them.

Finding the Right Time

• The speaker advises people to activate their brown fat whenever they have time during the day.

• People should try different times to see if it impacts their sleep or not.

• The activation of sympathetic nervous system due to coffee, exercise, cold water, and immersion can make it hard for some people to fall asleep.

• It is important for individuals to find out what works best for them as everyone's body responds differently.

Measuring Brown Fat Activity

In this section, the speaker discusses how they measured brown fat activity using an infrared camera and PET MRI scanning. They also talk about how they observed changes in insulin sensitivity and metabolism.

Measuring Brown Fat Activity

• The speaker used an infrared camera and PET MRI scanning to measure brown fat activity.

• PET MRI scanning is considered the golden standard for measuring brown fat but is expensive and not feasible for normal people.

• The purpose of measuring brown fat activity was to observe its circadian rhythm during both experience governmental days and regular days.

Changes in Insulin Sensitivity and Metabolism

• No specific bullet points with timestamps available on this topic.

Comfort During Cold Exposure

In this section, the speaker talks about how they measured the comfort level of participants during cold exposure and thermal comfortable days. They also discuss how they measured shivering using electromyography.

Measuring Comfort Level

• The speaker used a visual analog scale to measure the comfort level of participants during cold exposure and thermal comfortable days.

• Participants were asked to rate their comfort level on a scale from 1 to 10, with 5 being thermal comfortable.

Measuring Shivering

• Electromyography was used to measure shivering in participants.

• Conscious perception of shivering may not be the best readout of shiver as people can get adapted to cold water over time.

Study on Cold Water Exposure and Insulin Sensitivity

In this section, the speaker discusses a study on the effects of cold water exposure on insulin sensitivity and metabolism.

Effects of Cold Water Exposure

• Winter swimmers had increased insulin sensitivity compared to control group.

• Winter swimmers produced less insulin and had better blood glucose clearance than control group.

• High blood glucose is toxic to brain cells, and excessive insulin can be harmful as well.

• Neurons have a narrow range in which they are happy and survive.

Brain Survival After Death

• The speakers discuss the possibility of an episode on survival of the brain after death.

Optimal Cold Exposure

• The speaker discusses how much cold exposure is needed to extract benefits such as reduced blood sugar or improved Brown fat distribution.

Sauna and Cold Exposure for Cardiovascular Health

In this section, the speaker discusses the benefits of sauna and cold exposure on cardiovascular health based on various studies.

Sauna Benefits

• Up to 30 minutes in the sauna can lower the risk of cardiovascular disease.

• The threshold for healthy benefits is 19 minutes per session, 90 minutes per week.

• Going beyond 30 minutes does not provide additional health benefits.

• The healthy stress corresponds to around 10 minutes per session.

Cold Exposure Benefits

• One to two minutes of cold water exposure per session, up to 11 minutes per week, can have healthy benefits on cardiovascular system.

• Deliberate cold exposure should be divided into two or three sessions of maybe one to three minutes each time.

• Dividing up sessions into little bouts is more beneficial than doing one long session.

Balancing Exposure

• It's important not to become too cold adapted as it reduces the autonomic stimulus that cells need for adaptation.

• Dividing sessions into little bouts triggers adaptation better than doing one long session.

The Benefits of Short Stimulus Cold Immersion

In this section, the speaker discusses the benefits of short stimulus cold immersion for improving health metrics. They also discuss the practical feasibility of this method compared to longer sessions.

Short Stimulus Cold Immersion

• Short stimulus cold immersion is beneficial for improving health metrics.

• Longer sessions may not be as beneficial and could even be detrimental.

• Practical feasibility is a key advantage of short stimulus cold immersion over longer sessions.

Psychological Benefits

• A recent study on soldiers showed that weight loss was not the only benefit of cold immersion.

• Soldiers reported improved buffering against anxiety and significantly improved sexual satisfaction.

• Winter swimmers in the study reported good sleep quality and reduced social anxiety.

Sleep Quality and Comfort with Cold Exposure

In this section, the speaker discusses sleep quality and comfort with cold exposure. They also mention some observations that were not included in their study.

Sleep Quality

• The speaker did not measure sleep quality in their study but wishes they had.

• Anecdotally, winter swimmers reported good sleep quality.

• Control group participants also reported good sleep quality.

Comfort with Cold Exposure

• Winter swimmers reported being comfortable when exposed to cold temperatures.

• They were less scared of showing skin and had reduced social anxiety.

• One participant even got out of bed after 8 hours in the lab and walked around naked without caring about others seeing them.

Naked Winter Swimming?

In this section, the speaker asks about data on naked winter swimming or exposure to cold water without a bathing suit. They also mention some legal issues related to skinny dipping in public beaches.

Naked Winter Swimming?

• The speaker asks if there is any data on naked winter swimming or exposure to cold water without a bathing suit.

• The speaker mentions that skinny dipping is not legal in most public beaches in the United States.

Legal Issues

• Skinny dipping is not legal in most public beaches in the United States.

• There are a few exceptions, but it is generally not allowed.

Winter Swimming and Skinny Dipping

In this section, the speaker discusses winter swimming and skinny dipping in Denmark and the United States.

Winter Swimming Culture in Denmark

• Denmark has a winter swimming culture that has been around for hundreds of years.

• The oldest winter swimming club in Copenhagen is huge, and they swim naked at this facility. Men and women swim together, but there are also separate saunas.

• The newer clubs do not practice skinny dipping because everything is recorded nowadays.

Skinny Dipping

• There is no difference between wearing a bathing suit or not when it comes to cold exposure or adaptation.

• Skinny dipping has something to do with how you observe yourself and absorb your surroundings. It provides a sense of freedom.

• Some Banyas (Russian saunas) in the United States are clothing optional, such as Archimedes Banya in San Francisco.

Conclusion

• Deliberate cold exposure and sauna practices are becoming more popular due to their health benefits.

Psychedelics and Brown Fat

In this section, the speaker discusses the changing attitudes towards psychedelics in mainstream medicine and the observation of a volunteer who did not have any brown fat.

Psychedelics in Mainstream Medicine

• The speaker notes that psychedelics are being adopted by mainstream medicine and pharmaceutical companies.

• This marks a significant shift from their previous association with a certain community.

Observation of Volunteer without Brown Fat

• One winter swimmer did not have any brown fat when measured.

• The volunteer was not obese, which would have excluded them from the study.

• During the cooling experiment, the volunteer was unable to control their shivering compared to other winter swimmers.

• Blood samples showed that the volunteer's insulin levels were higher than other winter swimmers and their blood glucose clearance was slower.

• The volunteer was considered an outlier and removed from analysis.

The Importance of Cold and Heat Exposure

In this section, the speaker discusses the importance of cold and heat exposure in reducing inflammation in the body, which can help prevent lifestyle diseases such as type 2 diabetes, depression, anxiety, and Alzheimer's disease.

Cold and Heat Exposure

• The study measured IL-6 and IL-10 markers to see how inflammation was affected by heat exposure.

• Decreasing inflammation in the body can decrease modern lifestyle diseases such as type 2 diabetes, depression, anxiety, and Alzheimer's disease.

• Our modern sedentary lifestyle has made us more temperature comfortable which is why we don't expose ourselves to natural stresses that we did earlier on.

• Natural stressors like cold and heat exposure can keep our bodies in a natural balance again.

The Soberg Principle

• The Soberg principle suggests ending on cold after deliberate cold exposure to force your body to heat itself back up.

• Ending on cold keeps your brown fat activated along with your muscles which is good for keeping thermogenesis up.

• Ending on cold also increases neurotransmitters activation which makes brown fat cells more efficient along with muscle cells.

Brown Fat and Cold Exposure

In this section, the speaker discusses how cold exposure can activate brown fat and increase heat loss in the body. They also hypothesize that this could lead to improvements in sleep.

Activation of Brown Fat

• Cold exposure can activate brown fat.

• People who are exposed to cold lose heat faster from their bodies due to more vascular skin, which leads to higher activation of brown fat.

• This increased activation of brown fat is not a bad thing as it keeps the muscles activated and helps keep the system tuned well.

Benefits of Deliberate Cold Exposure

• Deliberate cold exposure can increase brown fat stores, which act like oil in the candle of thermogenesis.

• Increased heat loss due to deliberate cold exposure can be beneficial for efficient heating and cooling systems.

• There is no known benefit or disadvantage of doing deliberate cold exposure fasted or after a meal.

Cold Exposure for Symptom Relief

In this section, the speaker discusses whether deliberate cold exposure can help offset symptoms of various diseases such as Raynaud's syndrome and autoimmune conditions.

Raynaud's Syndrome

• People with Raynaud's syndrome suffer from very poor blood flow to extremities, leading to very cold fingertips that may even turn blue.

• It is unclear whether deliberate cold exposure can increase elasticity or plasticity of small capillaries and vessels in people with Raynaud's syndrome.

Autoimmune Conditions

• No information was provided on whether deliberate cold exposure benefits people with autoimmune conditions.

Rhinoids Syndrome and Cold Exposure

In this section, the speaker discusses rhinoids syndrome and how cold exposure can help alleviate the symptoms. They also mention that more studies are needed on this topic.

Rhinoids Syndrome and Cold Exposure

• Rhinoids syndrome is a common problem that affects more women than men.

• Exposing hands to cold and heat can make the vest more vascular, which can help alleviate symptoms.

• Some people have reported that exposing their hands to cold has helped them, but studies are needed on this specific topic.

• If people suffer from pain in their fingers due to rhinoids syndrome, they can take their hands out of the water during cold exposure or wear neoprene gloves.

Keeping Hands and Feet Warm During Cold Exposure

In this section, the speaker talks about ways to keep hands and feet warm during cold exposure.

Keeping Hands and Feet Warm During Cold Exposure

• If people experience pain in their fingers or feet during cold exposure, they can keep their hands out of the water or wear neoprene boots.

• While exposing your hands and feet to cold is a potent way to activate your nervous system, dipping them briefly before taking them out can still activate it.

• Keeping your head out of the water may be helpful for some people who experience headaches at the interface between water and cold. However, dunking all the way in may eliminate this issue for some individuals.

Physiological Reasons for Wearing a Cap During Cold Immersion

In this section, the speaker explains why wearing a cap during cold immersion may be beneficial.

Physiological Reasons for Wearing a Cap During Cold Immersion

• Studies have shown that when you submerge into cold water up to the neck, there is a decreased blood flow to the brain by around 30 to 40 percent.

• Wearing a cap during cold immersion can help keep your head warm and prevent heat loss from the body.

Importance of Keeping Head Out of Water

In this section, Dr. Silver discusses the importance of keeping your head out of the water when swimming in cold temperatures.

Reasons for Keeping Head Out of Water

• Submerging your head in cold water can decrease blood flow to the brain and increase heat loss from the body core.

• Dunking your head in cold water can increase heat loss rate by 36% and bring you closer to hypothermia.

• Wearing a beanie while swimming can keep you warmer and prevent dizziness caused by wind or sudden temperature changes.

Insulating the Brain in Hot Saunas

In this section, Dr. Silver talks about how insulating the brain with a wool cap can help people stay longer in hot saunas.

Insulating the Brain with Wool Caps

• Wearing a wool cap in a hot sauna insulates the brain from heat, allowing people to stay longer without feeling uncomfortable.

• The urge to get out of a hot sauna is driven by signals from the brain that detect high skin temperature.

• Insulating the brain with a wool cap delays these signals and allows people to tolerate higher temperatures for longer periods of time.

Stimuli for Hermetic Response

In this section, Dr. Silver discusses different stimuli that trigger hermetic response, including light, temperature, food, and movement.

Stimuli for Hermetic Response

• Light is an important stimulus for hermetic response, especially in Nordic countries where there are dramatic seasonal changes in the amount of light.

• Temperature, food, and movement are also important stimuli for hermetic response.

Deliberate Cold Exposure

In this section, the speaker discusses the different ways people can approach deliberate cold exposure. They also talk about children doing sauna and deliberate cold exposure, male-female differences in protocols, and additional safety measures.

Children Doing Sauna and Deliberate Cold Exposure

• Children can do sauna from a young age or deliberate cold exposure.

• Children are smaller than adults, so we cannot transfer all information and benefits to them.

• A study showed that boys aged 12 could defend their core temperature for up to one minute when exposed to cold water immersion up to the neck.

Male-Female Differences in Protocols

• There is no difference between men and women's response to cold exposure.

• Women can attest to their experience with deliberate cold exposure.

• Open bodies of water are more dangerous for smaller-bodied people due to currents.

Additional Safety Measures

• Smaller-bodied people are at greater risk of hypothermia when exposed to cold water.

• Hypothermia is no joke; it can cause slurring of words, drooling, semi-euphoria, etc.

• It is essential to approach deliberate cold exposure with caution. Start with cold showers then move on to still water natural water immersion.

Cold Exposure for Women

In this section, the speaker discusses whether women need a different protocol for cold exposure compared to men.

Women and Cold Exposure

• Women may have enough cold exposure with just 9 minutes per week due to being colder and having increased metabolism in their brown fat.

• The activation of brown fat should be the same in women as in men, but it is unclear if women need a different protocol for rapid cold exposure.

• Women can use the same short-duration cold exposure protocol as men to increase hermetic stress and adaptation response.

Frequency of Deliberate Cold Exposure

In this section, the speaker discusses how frequently one should do deliberate cold exposure.

Shorter Exposures More Frequently

• Shorter exposures more frequently are better than longer duration exposures less frequently.

• Changing temperature strengthens cells in the body, so varying temperature during short exposures is beneficial.

• Doing one session with changing temperatures or using nature's variation (e.g., four seasons) is sufficient.

Circadian Time and Cold Exposure

In this section, the speaker discusses circadian time and its relationship with cold exposure.

Circadian Time and Cold Exposure

• No bullet points available.

Benefits of Deliberate Cold Exposure

In this section, the speaker discusses the benefits of deliberate cold exposure at different times of the day and how it can be beneficial to keep the system tuned.

Importance of Going from Warm to Cold and Vice Versa

• It's not about getting cold, but going from warm to cold and vice versa.

• Biology is a process, not an event. Metabolic and thermoregulatory processes are like turning a knob; it's a verb as opposed to a noun.

• Internalizing this idea can lead to more flexibility, fun, and benefits.

Varying Temperature for Maximum Benefit

• Logically changing temperature up and down in water or air can activate brown fat even at 12-19 degrees Celsius.

• Exposing oneself to extremely cold temperatures all the time is unnecessary. Varying temperature keeps the system off balance and tuned.

Ongoing Study on Deliberate Cold Exposure

In this section, the speaker talks about an ongoing study on deliberate cold exposure that has not yet been published.

Preliminary Analysis of Data

• The study has not yet analyzed all data.

• The study looked at both men and women methods.

No Results Yet Available for Sharing

• There are no results available yet for sharing since they are still in preliminary analysis.

Importance of Deliberate Cold Exposure Research

In this section, the speaker emphasizes the importance of deliberate cold exposure research and thanks the guest for their work.

Importance of Deliberate Cold Exposure Research

• There have not been many high-resolution studies on deliberate cold exposure and heat's impact on health.

• The guest's study stands as a landmark in exploring deliberate cold exposure's potential impact on health.

Thanking the Guest

• The speaker thanks the guest for their public education efforts on social media and their book.

• The speaker appreciates that the guest practices what they preach, which is an asset to science.

Introduction

Dr. Susanna Söderholm introduces herself and her study on deliberate cold and heat exposure.

Deliberate Cold and Heat Exposure

• Dr. Söderholm's research on deliberate cold and heat exposure is discussed.

• A link to Dr. Söderholm's book, "Winter Swimming," is provided in the show notes.

• Viewers are encouraged to subscribe to the podcast on Spotify and Apple, leave a five-star review, and provide feedback in the comments section.

• The importance of checking out sponsors mentioned throughout previous episodes of the Huberman Lab podcast is emphasized.

Social Media Channels

• The Huberman Lab podcast's social media channels are introduced as hubermanlab on Instagram, Twitter, Facebook, and LinkedIn.

• The neural network newsletter is introduced as a zero-cost monthly newsletter that provides summaries of podcast episodes and toolkits for optimizing sleep, neuroplasticity, dopamine levels, cold exposure, heat exposure etc.

Conclusion

• Dr. Andrew Huberman thanks viewers for their interest in science.