April 25, 2022 • 1hr 50min

The Science & Health Benefits of Deliberate Heat Exposure

Huberman Lab

In this episode, Dr. Andrew Huberman discusses the science of deliberate heat exposure and its impacts on health, longevity, and performance. He explains the biological mechanisms behind how heat affects the body, from cardiovascular changes to hormone release to gene expression. Huberman covers research on sauna use and other forms of heat exposure, providing evidence-based protocols for leveraging heat to improve various aspects of physical and mental health.

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Key Takeaways

Deliberate heat exposure through sauna use or other methods can provide significant health benefits, including reduced risk of cardiovascular events, improved mental health, increased growth hormone release, and metabolic improvements
The optimal temperature range for sauna use is 80-100°C (176-212°F) for 5-20 minutes per session, with frequency ranging from 2-7 times per week depending on goals
Sauna use 2-3 times per week was associated with a 27% lower risk of cardiovascular-related death compared to once per week use. 4-7 times per week was associated with a 50% lower risk.
A protocol of four 12-minute sauna sessions at 90-91°C (194°F) followed by 6-minute cool downs significantly reduced cortisol levels
Sauna use activates heat shock proteins and increases FOXO3 expression, which are associated with longevity and cellular repair
Local hyperthermia therapy (heating a patch of skin to 41°C/105.8°F) can induce conversion of white fat to metabolically active beige fat, potentially increasing metabolism
Timing sauna use to the evening may improve sleep onset by leveraging the post-sauna cooling effect
Combining sauna use with fasting or exercise may amplify growth hormone release and other benefits
The discomfort of heat exposure activates endorphin pathways that can lead to improved mood and wellbeing

Introduction

In this episode, Dr. Andrew Huberman discusses the science of deliberate heat exposure and its impacts on health, longevity, and performance. He explains the biological mechanisms behind how heat affects the body, from cardiovascular changes to hormone release to gene expression. Huberman covers research on sauna use and other forms of heat exposure, providing evidence-based protocols for leveraging heat to improve various aspects of physical and mental health.

Topics Discussed

Mechanisms of Body Temperature Regulation (9:31)

Huberman explains that the body has two distinct temperatures - the shell (skin) temperature and the core (internal organs) temperature. The brain, specifically the pre-optic area (POA) of the hypothalamus, acts as a thermostat to regulate these temperatures through various mechanisms:

Vasodilation/vasoconstriction of blood vessels
Sweating
Shivering
Behavioral changes (e.g. seeking warmth or cooling)

Understanding this system is key to leveraging heat exposure for health benefits.

Health Benefits of Sauna Use (26:30)

Huberman reviews research on the health impacts of regular sauna use:

Cardiovascular health: 2-3 times per week associated with 27% lower risk of cardiovascular-related death; 4-7 times per week associated with 50% lower risk
Mental health: Inverse association between sauna frequency and risk of psychotic disorders
Longevity: Activation of heat shock proteins and FOXO3 expression associated with cellular repair and longevity

The optimal temperature range is 80-100°C (176-212°F) for 5-20 minutes per session.

Hormonal Effects of Heat Exposure (54:48)

Huberman discusses studies on how heat exposure impacts hormone levels:

Growth hormone: One protocol showed a 16-fold increase after four 30-minute sauna sessions at 80°C (176°F)
Cortisol: A protocol of four 12-minute sessions at 90-91°C (194°F) significantly reduced cortisol levels

He notes that the growth hormone effect diminishes with repeated exposure, so less frequent but more intense sessions may be optimal for this goal.

Timing Considerations for Heat Exposure (1:08:26)

Huberman explains how circadian rhythms impact the effects of heat exposure:

Evening sauna use may improve sleep onset by leveraging the post-sauna cooling effect
Morning cold exposure aligns with the natural rise in body temperature upon waking
Fasting or low blood sugar prior to heat exposure may amplify growth hormone release

Mood and Mental Health Effects (1:17:10)

Heat exposure can improve mood and mental health through several mechanisms:

Release of dynorphin, which leads to increased sensitivity to feel-good endorphins
Activation of the sympathetic nervous system, followed by relaxation
Potential long-term improvements in endorphin signaling pathways

Local Hyperthermia and Fat Metabolism (1:35:33)

Huberman discusses new research on local hyperthermia therapy:

Heating a patch of skin to 41°C (105.8°F) for 20 minutes induced conversion of white fat to metabolically active beige fat
This led to systemic increases in metabolism and improvements in glucose regulation
The effect is mediated through heat shock factor 1 (HSF1) and other molecular pathways

While more research is needed, this presents a potential new avenue for metabolic health interventions.

Practical Protocols and Considerations (1:04:32)

Huberman synthesizes the research to provide practical guidelines:

For general health: 2-3 sauna sessions per week, 15-20 minutes at 80-100°C (176-212°F)
For maximum growth hormone release: Four 30-minute sessions at 80°C (176°F) with cool-downs, but only once every 7-10 days
For improved sleep: Evening sauna use, allowing time to cool down before bed
For mood benefits: Push to slight discomfort in heat exposure to activate endorphin pathways
Hydration is crucial: Drink at least 16oz of water for every 10 minutes of sauna use

He emphasizes starting conservatively and gradually increasing intensity and duration as heat tolerance improves.

Conclusion

Deliberate heat exposure, particularly through sauna use, offers a wide range of potential health benefits supported by scientific research. From cardiovascular health to hormone optimization to mental wellbeing, regular heat exposure can be a powerful tool for improving overall health and longevity. By understanding the underlying biological mechanisms, individuals can tailor heat exposure protocols to their specific goals and needs.

Huberman emphasizes that while the research is promising, safety should always be the top priority. Start with conservative protocols and gradually increase intensity and duration. Those with pre-existing health conditions should consult their healthcare provider before beginning any heat exposure regimen.

As research in this area continues to evolve, we may see even more targeted applications of heat exposure for health optimization. The recent findings on local hyperthermia and fat metabolism highlight the potential for new interventions targeting specific physiological processes.

Ultimately, deliberate heat exposure represents a accessible, low-cost tool that can complement other health-promoting behaviors like exercise, proper nutrition, and quality sleep. By incorporating evidence-based heat exposure protocols into their routines, individuals may be able to unlock significant improvements in their physical and mental wellbeing.