Cold Heat Exposure

The Big Picture

All three sources are Huberman Lab episodes, and they approach temperature as a stimulus the body responds to in measurable ways. Andrew Huberman calls temperature a potent stimulus in his solo episode on cold [3] and repeatedly warns in his solo episode on heat that overheating can damage neurons permanently [2]. Between those two sits a conversation with Dr. Susanna Søberg, who earned her PhD at the University of Copenhagen studying how deliberate cold and heat exposure affect human metabolism and is the first author of a 2021 study in Cell Reports Medicine that identified minimum thresholds for cold and sauna exposure to activate brown fat thermogenesis [1].

Taken together, they describe two tools with overlapping effects. Cold triggers the release of norepinephrine, epinephrine and dopamine and is presented as a route to mental resilience, mood and focus, metabolism, recovery from exercise and physical performance [3]. Heat is presented with evidence that regular sauna use lowers cardiovascular and all-cause mortality, reduces cortisol, activates heat shock proteins and the longevity-linked FOXO3 pathway, and improves mood through the dynorphin and endorphin systems [2].

Where the Experts Agree

• Both cold and heat change fat tissue. Huberman says cold can convert energy-storing white fat into heat-producing beige and brown fat [3]. He reports that, according to a new study in the journal Cell, heat can convert white fat into metabolically active beige fat [2]. Søberg's own research concerns the thresholds of cold and sauna needed to activate brown fat thermogenesis, and she explains how brown fat works and what her study of Danish winter swimmers found [1].
• The useful dose is the smallest one that works. Huberman tells listeners to look for the minimum effective dose of cold [3]. Søberg's study is about minimum thresholds [1].
• Safety comes first. The cold episode opens with a strong safety message: consult a physician and progress gradually [3]. The heat episode stresses safety, hydration and checking with a doctor [2]. Søberg offers what the summary calls a scientist's caution, and their conversation covers Raynaud's, children and sex differences [1].
• Mood is a real benefit. Cold releases dopamine, norepinephrine and epinephrine [3]. Heat acts on the dynorphin and endorphin systems [2].
• The discomfort is part of the point. Søberg and Huberman discuss what happens in the body when we get uncomfortably cold [1]. Huberman lists mental resilience first among the uses of cold [3].

Where They Differ

With one host across all three, the sources largely agree. The differences are in what each tool is best for and how firmly each claim is stated.

Longevity versus daily performance. The strongest long-term health claims attach to heat: lower cardiovascular and all-cause mortality with regular sauna use, and a growth hormone boost of as much as sixteenfold [2]. Cold is pitched more toward how you feel and perform now: focus, mood, recovery and work capacity [3]. Søberg's work joins the two through metabolism [1].

Whole body or one patch of skin. Søberg and Huberman talk about full immersion, showers versus plunges and head dunking [1]. Huberman's solo episodes add local approaches. Cooling specific skin surfaces, the palms, soles and upper face, can dramatically increase how much work you can do [3], and deliberate heat can come from heavy clothing on a jog or even heat applied to one patch of skin, not only from saunas and hot baths [2].

Timing against other goals. The cold episode covers what the research says about cold after training and ends with guidance on timing cold exposure around sleep, which signals that when you do it changes what you get [3]. The passages here do not give the specific rules.

Enthusiasm and caution. The heat episode is described as enthusiastic but careful [2]. Søberg balances caution with the experience of someone who went from a self-described "cold sissy" to a regular winter swimmer [1]. Huberman brings his own background: an undergraduate cold physiology lab, a graduate thesis on thermoregulation, Danish family and morning cold plunges [1][2][3].

Open practical questions. Søberg's conversation takes up shivering and ending on cold [1]. These passages name the topics without reporting her answers, so they are best treated as pointers to the full episode.

Practical Takeaways

• Talk to a doctor before starting deliberate cold or heat, and build up gradually [2][3].
• Aim for the minimum effective dose instead of the longest or coldest session you can stand [1][3].
• In the sauna, hydrate and never push to the point of overheating, which Huberman warns can permanently damage neurons [2].
• You do not need a sauna. Hot baths, or heavy clothing on a jog, are other forms of deliberate heat [2].
• You do not need a plunge tub. Showers are discussed alongside plunges as an option for cold [1].
• Use cold when you want alertness, focus and a mood lift, since it releases norepinephrine, epinephrine and dopamine [3].
• To extend a hard workout, try cooling the palms, the soles of the feet or the upper face [3].
• Think about when you use cold in relation to training and sleep, because timing affects the result [3].
• If you have Raynaud's, or are deciding for children, look at the specific guidance first [1].

Sources

1. Dr. Susanna Søberg: How to Use Cold & Heat Exposure to Improve Your Health · Huberman Lab
2. The Science & Health Benefits of Deliberate Heat Exposure · Huberman Lab
3. Using Deliberate Cold Exposure for Health and Performance · Huberman Lab

See all 4 summaries about cold heat exposure →