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Last Updated: 12.06.23

The Science & Health Benefits of Deliberate Heat Exposure

Heat exposure /​​ sauna impacts temperature, metabolism, heart health, hormones, cognition, mood, longevity. Huberman discusses protocols: exposure times, temperatures, delivery methods, and outcomes: growth hormone release, cortisol reduction.

Key Takeaways

High level takeaways from the episode.

Two body temperatures: skin (shell) and core (viscera, organs, nervous system)

Transitioning between hot and cool environments can increase growth hormone release

Pregnant, nursing, or heat-​​sensitive individuals should avoid saunas and other heat-​​related tools

Deliberate heat exposure can improve health and longevity

  • Study: Sauna Bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women
  • Regular use of sauna or other forms of deliberate heat exposure can reduce mortality from cardiovascular events and other health issues

Relationship between temperature and lethargy is intimate

  • Warm enough: active and want to move around
  • Too warm: need to stay put, spread out limbs, and dump heat

Sauna Mechanisms

  • Increases blood flow, plasma volume, stroke volume, and heart rate
  • Mimics cardiovascular exercise without joint and limb stress

Study: Endocrine Effects of Repeated Hot Thermal Stress and Cold Water Immersion in Young Adult Men

  • 4 sauna sessions of 12 minutes each at 90–91 degrees Celsius (194 degrees Fahrenheit)
  • 6‑minute cooldown break in cold water (10 degrees Celsius, 50 degrees Fahrenheit)
  • Results: significant decrease in cortisol (stress hormone) output

Sauna exposure 2–3 times per week (80–100 degrees Celsius) upregulates FOXO3, involved in DNA repair pathways and clearing senescent cells

  • Individuals with additional or hyperactive FOXO3 are 2.7 times more likely to live to 100 years or longer

Study by Susannah Soberg: 57 minutes per week of sauna exposure and 11 minutes per week of cold exposure improved metabolism and increased brown fat

Sauna sessions can be divided into shorter sessions throughout the week

Sauna can increase growth hormone levels

  • Growth hormone is responsible for tissue repair and growth spurt during puberty
  • Secretion of growth hormone decreases with age

Growth hormone response diminishes with frequent sauna use

  • Body adapts to the heat exposure, reducing the shock to the system
  • To maximize growth hormone increase, limit sauna use to once a week or once every ten days

Cold exposure can also impact growth hormone levels

  • Cooling the body’s shell heats up the core

Cold water exposure (4°C for 20 seconds) can cause a 200–300% increase in norepinephrine (noradrenaline)

  • Norepinephrine and dopamine increase mood, focus, and alertness
  • Longer exposure to less intense cold (6 hours at 16°C) can lead to even greater increases in norepinephrine

Cold exposure is best done early in the day to match the natural increase in body temperature across the 24-​​hour circadian rhythm

Heat exposure is best done later in the day, as it activates cooling mechanisms and helps the body cool down, making it easier to fall asleep

To optimize growth hormone release and sleep, do sauna in the evening or at nighttime

  • Take a warm or cool shower afterwards to rinse off sweat and prepare for sleep

Sauna use can aid in sleep

  • Decreases in body temperature after sauna use can help with the transition to sleep

Hydration is important after sauna use

  • Drink at least 16oz of water for every 10 minutes spent in the sauna

Sauna use can improve mood and mental health

  • Deliberate heat exposure can upregulate pathways that allow for experiencing pleasure
  • Endorphins are released
  • Sauna use can improve baseline mood and heighten positive emotions in response to positive events

A 2018 study found a relationship between sauna bathing and a reduced risk of psychotic disorders

  • Further research is needed to understand the mechanisms behind this relationship
  • Not causal, but correlative
  • Frequent sauna use may be related to other health-​​promoting activities

Glabrous skin surfaces (upper half of the face, palms of hands, bottoms of feet) can be used to heat or cool the body quickly

Fever is an adaptive response to kill pathogens

  • Most pathogens don’t survive well at high temperatures
  • Taking medications to reduce fever may short-​​circuit this protective mechanism

Local hyperthermia therapy involves heating a specific body surface

  • Converts white fat to beige fat, leading to increased metabolism and fat loss


  • The concept of subjecting oneself to enough stress to induce adaptation
  • Examples include adapting to cold water exposure, cardiovascular exercise, and resistance training
  • Leads to growth or strengthening of muscles, improvement in cardiovascular function, and other adaptations

Mitohormesis: stressful stimuli activating pathways like UCP One and HSF One can induce changes in mitochondria, leading to increased metabolism


Science-​​based tools and supplements that push the needle.

Sauna + Cold for Metabolic Enhancement


Sauna for Lifespan, Heat Shock Proteins, Cardiovascular Health, Hormones, Moods


Sauna for Stress Reduction


Hydration for Sauna


Optimal Timing for Sauna and Cold Exposure for Circadian Rhythm


Sauna to Optimize Growth Hormone


Cold Exposure for Brown Fat



We recommend using this distillation as a supplemental resource to the source material.

  • The Science & Health Benefits of Deliberate Heat Exposure

    Huberman Lab #69

    How heat exposure /​​ sauna affects body temperature, metabolism, heart health, hormones, cognition, mood, longevity, and specific protocols for different outcomes.

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