Dr. Susanna Søberg and Andrew Huberman Discuss Deliberate Cold And Deliberate Heat Exposure

First, a few key takeaways from this conversation:

For most everyone, the goal should not be to become so cold or heat adapted to be able to stay in a cold plunge or sauna for the longest amount of time possible. Rather, the goal is to improve the health metrics that come from repeated exposure to the stimulus. In practice, this means breaking deliberate exposure up into more sessions that are shorter in length. Longer sessions are not necessary and may even be counterproductive.

Dr. Susanna Søberg's recommends a protocol goal of 11 minutes in total per week for deliberate cold exposure and 57 minutes per week for deliberate heat exposure split up into 2-3 sessions. 

	Cold Exposure	Heat Exposure
Sessions	2-3 times a week	2-3 times a week
Duration	1-2 minutes at a time	10-15 minutes at a time

 

When paired together as contrast therapy, you might ask – should I end on cold or end on heat? 

This is also what Huberman refers to as the "Søberg Principle", given her findings on this topic. The Søberg Principle answers the age old question of which to do last when doing contrast therapy. When you end on the cold, you force your body to heat up by itself. This requires your brown fat and muscles to remain activated. This becomes an exercise even when you go home for hours after the exposure, keeping neurotransmitters active. This makes your brown fat and muscles more efficient delivering greater ongoing benefit.

 

 

Introduction to the conversation between Søberg and Huberman

The human body is a masterpiece of adaptation, demonstrating remarkable resilience in the face of environmental challenges. Its thermoregulatory capacity, or the ability to maintain a stable internal temperature despite external fluctuations, is one of the more compelling examples of this inherent adaptability. This process is now being studied intensively for its potential to bring about significant health benefits. One of the luminaries in this field is Dr. Susanna Søberg, a pioneering researcher focused on the interface between human metabolism, deliberate cold and heat exposure, and health.

Dr. Søberg's work stands out in the field of temperature-driven metabolic research. She emphasizes the role of cold and heat exposure in driving a plethora of physiological changes that potentially contribute to hormone balance, metabolism regulation, and neurotransmitter production. Let us venture into the frosty cold and scorching heat in the quest for optimal health, guided by the intriguing findings and profound insights of Dr. Søberg in a recent conversation with Andrew Huberman.

 

Navigating the Chills: Delving into the Science of Cold Exposure

Before we dip our toes into the icy waters of deliberate cold exposure, Dr. Søberg stresses the paramount importance of exercising caution. This principle rings particularly true for children and those with smaller bodies, who are inherently more susceptible to hypothermia.

She notes, "The cold is a powerful stimulus, and kids and smaller-bodied people are at greater risk of hypothermia. It's important to approach cold exposure with caution." This cautionary note underscores the potential risks associated with cold exposure, primarily the threat of hypothermia, a condition characterized by abnormally low body temperature (Guyton and Hall, 2011).

Cold exposure works by stimulating cold receptors in the skin, which send signals to the hypothalamus, the body's temperature control center (Mäkinen et al., 2008). This stimulates a cascade of physiological responses aimed at maintaining core body temperature, including vasoconstriction, shivering thermogenesis, and the activation of brown adipose tissue (BAT), commonly known as brown fat.

Brown fat, unlike its more well-known counterpart, white adipose tissue (WAT), is metabolically active. Its primary role is thermoregulation, converting stored energy into heat through a process known as non-shivering thermogenesis (Cannon and Nedergaard, 2004). The activation of BAT not only helps to maintain body temperature but also promotes energy expenditure and weight loss. In a 2014 study published in the Journal of Clinical Investigation, researchers demonstrated that cold exposure could increase energy expenditure by up to 15% due to the activation of BAT (Yoneshiro et al., 2014).

However, despite these potential benefits, it is critical to introduce cold exposure gradually to avoid the risk of hypothermia. Dr. Søberg advises individuals to start with cold showers as a safer alternative. Over time, as tolerance improves, individuals can progressively transition to more intense cold exposure practices such as total body cold immersion or cold plunges.

 

The Role of Shivering in Deliberate Cold Exposure

A fascinating reaction to cold exposure is shivering, a physiological response characterized by involuntary muscle contractions designed to generate heat and counteract the cold. Besides warming the body, shivering can significantly increase metabolism and burn calories, contributing to weight loss and metabolic health.

But shivering's benefits extend beyond heat generation. It plays a critical role in activating brown fat as we introduced above, the body's internal furnace. The activation of brown fat by shivering helps to warm the body up again after cold exposure. Shivering can occur during cold exposure or after, contributing to a phenomenon known as the 'afterdrop.' This is why we often shiver more after getting out of cold water even though the air around us is warmer. This is a further decrease in core body temperature after leaving cold water, attributed to the body's continued efforts to counteract the cold.

 

The Art and Science of Cold Exposure

To reap the benefits of cold exposure, it's essential to follow specific protocols that involve gradually acclimatizing the body to cold temperatures. Cold showers serve as an excellent starting point. While the research is still nascent, some studies suggest that cold showers may activate brown fat and increase metabolism.

One key principle in cold exposure practice is that it should be uncomfortable to be effective. However, as individuals repeatedly expose themselves to cold temperatures, they may notice a reduction in discomfort as their bodies adapt.

The duration of cold exposure may vary based on individual tolerance levels and specific desired outcomes. A longer exposure duration could potentially yield more significant benefits. But it's crucial to always listen to your body and avoid pushing beyond safe limits.

Ending on cold exposure is also essential to maximize the benefits and condition the body. This practice serves as a form of 'training' for the body and cells, leading to increased insulin sensitivity and overall health.

 

Gendered Responses: Unraveling the Differences in Cold Exposure Outcomes between Men and Women

Dr. Søberg's research also brings to light fascinating differences in how men and women respond to cold exposure. She states, "Women may require less cold exposure to achieve similar benefits. They may have increased metabolism in their brown fat and can potentially experience cold exposure benefits with just nine minutes per week."

The differences observed may be attributed to various factors, including potential variations in temperature perception and metabolic responses. For instance, a 2018 study published in Frontiers in Physiology found that women have a higher sensitivity to cold, experiencing discomfort at higher temperatures than men (Filingeri, 2018). Furthermore, women seem to have more active brown fat compared to men, contributing to an increased metabolic response to cold exposure (Cypess et al., 2009).

This finding has profound implications for optimizing cold exposure protocols. It suggests that the dosage of cold exposure could be personalized based on gender, leading to safer and more effective outcomes.

 

Harnessing Cold Exposure for Health: An In-depth Look at Cold Adaptation

The intricate mechanism of cold adaptation is a testament to the remarkable resilience of the human body. It's an intriguing process where consistent exposure to cold temperatures - such as wearing a t-shirt in a cold environment - can help the body acclimatize to cold conditions. Over several days, this deliberate exposure can spur the activation of brown adipose tissue or brown fat, a type of body fat known for its heat-generating abilities.

This adaptive process has a profound effect on thermal regulation, the body's ability to maintain its internal temperature. Not only does cold exposure stimulate the expansion of brown fat, but it can also enhance one's thermal comfort in cold environments, making the chilly conditions more bearable.

The health dividends of cold exposure and brown fat activation are plentiful, encompassing physical leanness and a bolstered immune system function. It's a testament to the potential power of cold exposure in contributing to our overall health and wellbeing.

Intriguingly, this idea is woven into the cultural fabric of some societies. For instance, a Scandinavian saying advises wearing fewer layers in the fall and more in the spring. This practice encourages the body to prepare for the impending cold and heat, respectively, thereby fostering thermal regulation.

Even in childhood, exposure to cold is seen as beneficial. In Denmark and other Scandinavian countries, it's not uncommon for babies to be placed outside to sleep in the cold. This practice, rooted in tradition, is believed to enhance their resistance to cold, potentially fortifying their immune systems.

Furthermore, the tradition of winter swimming in Scandinavia embodies the embrace of cold exposure for health benefits. Winter swimmers, by immersing themselves in frigid waters, activate brown fat and experience an array of positive effects. These include boosts to metabolism and energy levels, along with enhanced mental well-being, attesting to the holistic benefits of embracing the cold.

 

Review of Søberg's Study on Winter Swimmers and Cold Exposure

The study conducted by Søberg presents an intriguing exploration into the effects of cold exposure, particularly through winter swimming, on brown fat activation and its subsequent impact on metabolism. This study is unique in that it specifically targeted winter swimmers who had already adapted to the cold, recruiting them to engage in cold water exposure and sauna sessions multiple times per week.

A fundamental principle underpinning this study is the activation of the diving response. By submerging the body, including the face, in cold water, this physiological response is triggered. It has been observed to lead to a calming and relaxing parasympathetic response in the body.

Unfortunately, the detailed results of the study in terms of brown fat activation and its metabolic impact were not explicitly provided in the transcript. However, a key insight revealed is that cold water exposure doesn't necessarily have to be extremely cold to stimulate metabolism and afford health benefits. The range of water temperatures used during the study varied from a relatively mild 15°C (59F) down to a bracing 2-4°C (39F) during the coldest period.

Accommodating the participants' schedules, the study allowed them to choose the time of day for alternating between cold exposure and sauna based on their personal convenience. Temperature measurements were dutifully recorded during each session, with a graph illustrating the temperature in Denmark from October to April provided for context.

Despite sleep quality not being a primary metric in the study, participants reported good sleep quality. This was an interesting subjective observation, even though it wasn't directly quantified in the research. Alongside this, the study documented a clear trend in winter swimmers experiencing reduced shivering and demonstrating an evident adaptation to the cold over time.

Remarkably, the study extended beyond the physiological effects and ventured into the psychological sphere. Reduced social anxiety and an increased level of comfort with cold exposure were observed among the participants, pointing to potential mental health benefits of this practice.

Even though the compensation for winter swimmers participating in the study was limited, they did receive some financial acknowledgement.

A particularly noteworthy finding was the identified thresholds for exposure. The study found that 11 minutes of total weekly cold exposure, broken down into sessions of 1-2 minutes, along with 57 minutes of total sauna exposure, distributed into sessions of 10-15 minutes, were deemed sufficient for yielding health benefits. Interestingly, the threshold for sauna benefits plateaued around the 30-minute mark, suggesting that extending sauna exposure beyond this point didn't significantly enhance benefits.

The impact of clothing or lack thereof during cold water exposure or sauna sessions was found to be negligible. Whether participants were clothed or naked didn't affect the derived benefits, supporting the idea that the physiological response to cold or heat is not materially influenced by clothing. The study further demonstrated that being overly cold adapted was not the goal, but maintaining a consistent stimulus of cold exposure was key.

From a psychological perspective, skinny dipping or being comfortable with nudity during winter swimming was found to have potential benefits for some individuals, adding a layer of depth to the study.

While the study didn't directly assess sleep quality, participants reported good sleep and sporadic waking episodes during the night. This provides another layer of anecdotal evidence regarding the potential benefits of cold exposure and sauna.

Interestingly, not all participants showcased brown fat, with one individual even demonstrating zero brown fat activity. This participant faced challenges in controlling shivering during the cooling experiment, hinting at the crucial role brown fat plays in cold adaptation and thermoregulation.

Overall, the study provides a captivating look into the multifaceted impacts of cold exposure and sauna use, from physiological changes to psychological benefits. It underscores the potential of these practices to enhance health and wellbeing while raising intriguing questions for future exploration.

 

The Heat of the Matter: Turning up the Thermostat with Heat Exposure

While cold exposure is an exciting realm of exploration, Dr. Søberg’s work doesn’t stop there. She also delves into the physiological effects of heat exposure on human health. In particular, she studies the role of heat shock proteins (HSPs) in promoting cellular health and resilience.

In response to heat exposure, the body produces HSPs, which help protect cells from damage (Lindquist, 1986). These proteins have been linked to numerous health benefits, including promoting muscle repair, reducing inflammation, and improving cardiovascular health (Maloyan et al., 2005; Gjovaag et al., 2016).

The mechanisms behind these benefits are multifaceted. For instance, HSPs help repair damaged proteins and assist in their correct folding, preventing the formation of harmful protein aggregates that can cause cellular damage (Morimoto, 1998). They also modulate immune responses, thereby reducing inflammation and promoting overall health (Asea et al., 2002).

Regular sauna use, a form of heat therapy, is one practical way to leverage these benefits. Dr. Søberg mentions that regular sauna use, specifically "at least 4-7 times per week," has been associated with numerous health benefits, including a reduced risk of cardiovascular diseases and improved mental health. These findings are supported by several studies, including a 2018 systematic review published in Mayo Clinic Proceedings, which affirmed the positive effects of regular sauna use on cardiovascular and neurocognitive health (Laukkanen et al., 2018).