Andrew Huberman (solo) — Stanford professor of neurobiology and ophthalmology and host of the Huberman Lab podcast. This is a solo Essentials episode with no guest.
The gist
Andrew Huberman explains how the body regulates temperature through a circuit running from the skin to the spinal cord to the preoptic area (POA) of the hypothalamus, and how deliberate heat exposure leverages that circuit for health benefits. He reviews research showing sauna use is associated with large reductions in cardiovascular and all-cause mortality, then unpacks the mechanisms: heat shock proteins, FOXO3-driven DNA repair, cortisol reduction, and large growth-hormone increases. He gives concrete protocols, including temperatures of 80 to 100 degrees Celsius and sessions of 5 to 20 minutes, plus frequency guidance for different goals. He also covers low-cost alternatives to a sauna, optimal timing relative to sleep, hydration, and the dynorphin-endorphin pathway behind sauna's mood benefits.
Big reveals
- People who sauna 2-3 times per week were 27% less likely to die of a cardiovascular event than those who went once a week.
- Going 4-7 times per week cut cardiovascular mortality risk by 50% versus once a week.
- A 2-hour-a-day sauna protocol produced a 16-fold increase in growth hormone on day one.
- The growth hormone effect shrank dramatically with repetition, dropping to roughly a 3-4 fold increase by day three as the body adapted.
- Repeated hot/cold sauna sessions caused a significant decrease in cortisol output in young adult men.
- People with extra or hyperactive copies of the FOXO3 gene are 2.7 times more likely to live to 100 or beyond.
- The discomfort of a hot sauna comes partly from dynorphin binding the kappa receptor, which over time upregulates feel-good endorphin pathways.
Things worth remembering
- You always have two body temperatures at once: your skin (the 'shell') and your core (viscera, nervous system, spinal cord).
- Unlike cold, you can't heat the brain much before risking neuron damage, and central nervous system neurons don't regenerate once damaged.
- Sitting in a hot sauna raises heart rate to 100-150 bpm and increases stroke volume, mimicking cardiovascular exercise without joint loading.
- Heat shock proteins rescue misfolding proteins, much like how heat changes the texture of raw versus cooked meat at the molecular level.
- The 2018 cohort study analyzed by Huberman included 1,688 participants with a mean age of 63, about 51% women.
- Elevated blood glucose or insulin blunts growth hormone release, so doing sauna fasted maximizes the GH response.
- Doing sauna later in the day can aid sleep because the post-sauna cooling drop in body temperature helps you fall asleep.
- A rough hydration guide is at least 16 oz of water for every 10 minutes spent in the sauna.
- You don't need a sauna: a hot bath up to the neck, layered clothing, or even wrestler-style plastic suits while jogging can raise shell and core temperature.