Tetragrammaton with Rick Rubin

Guest: Andrew Huberman, Ph.D. (Part 1)
Date: September 17, 2025

Episode Overview

This episode features an expansive and deeply personal conversation between Rick Rubin and neuroscientist Dr. Andrew Huberman. The main theme revolves around optimizing human biology through understanding circadian rhythms, sunlight, hormones (especially cortisol), sensory health, and the impact of modern lifestyle choices. The discussion seamlessly weaves practical neuroscience with reflection on personal growth, loss, creativity, and the human condition.

Key Discussion Points & Insights

1. Cortisol: The Misunderstood Hormone

[00:02–09:45]

• Cortisol as an Energy Deployment Hormone
  Huberman clarifies common misconceptions about cortisol, typically labeled as a "stress hormone." He emphasizes its role as an "energy deploying hormone" necessary for waking, alertness, and focus.

  "Cortisol's job is not to combat stress. Cortisol's job is to cause the release of energy from your muscles, from your liver, so your brain and muscles have energy."
  — Andrew Huberman, [00:04]

• Circadian Rhythm of Cortisol
  Cortisol rises naturally in the morning, known as the cortisol awakening response, and ideally peaks in the first hour after waking—this spike determines energy, focus, and proper decline towards the evening.

  • Failing to spike cortisol early may result in flattened cortisol curves, harming immunity, disease recovery, and longevity.
  • Sunlight exposure within the first 60–90 minutes after waking is vital for optimal cortisol dynamics.

  "If you don't get your cortisol high enough in the morning, it leads to what's called a flattening of the cortisol curve. And that's bad."
  — Andrew Huberman, [00:07]

• Mechanisms for Modulating Cortisol

  • Bright light (ideally sunlight) is the most important lever.
  • Artificial light can be used if sunlight isn't available (10,000 lux).
  • Caffeine does not increase cortisol; it just prolongs its effects.
  • Licorice root (glycyrrhizin) and grapefruit can further extend morning cortisol.
  • Exercise and cold exposure also increase cortisol but should be timed early in the day.

  "Sunlight is the one you cannot replace with anything else."
  — Andrew Huberman, [09:35]

• Evening and Night Practices

  • Avoid light, caffeine, cold exposure, and licorice root late in the day to ensure low cortisol and allow melatonin to rise for sleep.

2. Sunlight, Melatonin, and Circadian Regulation

[09:45–21:24] [21:24–26:47]

• Sunlight's Irreplaceable Role

  • Huberman reiterates the critical importance of early light exposure for mood, energy, immune function, and sleep quality.

  • Sunlight viewing at sunset doesn't spike cortisol but boosts melatonin production, contributing to evening tranquility and sleep.

  "We can no longer say cortisol is a stress hormone—it’s an energy deploying hormone. And we can no longer say sunlight is a hack; it’s what our biology is there for."
  — Andrew Huberman, [21:24]

• Hack vs. Human Design

  • Huberman and Rubin discuss how light habits are often mislabeled as “biohacks,” when they are, in fact, fundamental to human biology.

  "None of this is a hack. This is the way that we are supposed to live."
  — Andrew Huberman, [24:36]

• Chronotypes

  • Guidance is individualized: morning or night people should get sunlight within 60–90 minutes of waking.
  • No one escapes circadian biology.
  • Anchor well-being by synchronizing to light/dark cycles.

  "No one on Earth escapes circadian rhythm. No one."
  — Andrew Huberman, [26:35]

3. Environmental Inputs: Sunglasses, Sunscreen, and Artificial Light

[26:47–34:30]

• Sunglasses & Sunscreen

  • Wearing sunglasses or certain sunscreens can block beneficial wavelengths, disrupting hormone signaling.
  • Physical barriers like light-colored clothing are preferred over chemical sunscreens.
  • Notably, Huberman refers to dermatologist Dr. Teo Soleimani’s insight: deadly melanoma is not from sun exposure, but from places where the sun doesn’t reach.

  "The deadly melanomas don't come from sun exposure ... It's on the places that don't get much sun exposure."
  — Andrew Huberman, [29:28]

• Chemical Fragrances & Endocrine Disruption

  • Many synthetic personal products act as endocrine disruptors, affecting hormones and health—especially certain oils and chemicals in detergents, soaps, and deodorants.
  • Huberman advocates minimalism and awareness in product use for overall health.

4. The Primacy of Smell & Intuition

[36:06–51:54]

• Olfaction's Profound Influence

  • Human smell is evolutionary, unconscious, and dictates attraction, bonding, and even memory.
  • Every day, people “smell themselves,” picking up cues about health and mood.
  • Gut lining contains olfactory receptors—our bodies “smell” food internally, shaping cravings and aversions.

  "We are constantly smelling ourselves, whether we admit it or not ... giving ourselves feedback as to whether or not ... we feel well."
  — Andrew Huberman, [42:18]

• Masking Natural Scents

  • Synthetic scents can numb natural olfactory feedback and impact emotional and social intuition.
  • Huberman urges listening to natural "gut feeling"—it returns quickly when we reduce sensory masking.

  "If you stop overriding it for a short while because it’s so primordial, it comes back fast."
  — Andrew Huberman, [50:53]

• Social and Group Energetics

  • Shared environments (events, concerts, relationships) transmit undetectable but powerful emotional and chemical signals.

5. Sunlight, Light Exposure, and Digital Toxins

[63:16–66:33]

• Firelight, Moonlight, and Screen Exposure

  • Natural light sources like firelight and moonlight at night help entrain healthy circadian rhythms.
  • Short-wavelength blue/green light from screens at night is "toxic," suppressing melatonin and damaging retinas—even 15 seconds of exposure can suppress sleep hormone production.

  "After about 15 seconds, your melatonin levels are floored out."
  — Andrew Huberman, [66:06]

• Mitigating Artificial Light

  • Recommendations: Remove blue light from screens at night, wear red-lens glasses, use breathable sleep masks, and keep environments dim after sunset.

6. Personal Growth, Loss, and the Meaning of 50

[53:33–77:02]

• Reflecting on 50 & Loss

  • Huberman discusses outliving mentors, friends lost to suicide or drugs, and the unique psychological impact of approaching 50.
  • Stories of creative, passionate friends who burned bright and faced tragic ends highlight the complex interplay of emotional fire, mental health, and societal factors.

• Intergenerational Wisdom & Family

  • Deciding to interview his father—a physicist and chaos theory pioneer—Huberman describes deepening his appreciation for his parents, his own life choices, and the unpredictability of generational legacy.

  "I think in that moment, I was just like, man, I'm like, the luckiest son ever."
  — Andrew Huberman, [71:52]

7. The Evolution of the Huberman Lab Podcast

[77:08–84:37]

• Growth and Public Engagement

  • Year-by-year reflection: Explosive early energy, embrace of critique, realization that media narratives can be distorting but also expanding, emotional transparency, and a current shift back to essence—teaching and discovery.

  "I'm done with kind of like. It's not about me. It was never supposed to be about me. ... It's supposed to be about sunlight. It's supposed to be the information."
  — Andrew Huberman, [84:37]

• The Role of Novelty

  • Recommitment to learning, uncovering new scientific gems (e.g., novel cortisol research), and pushing away repetitive personal narrative to facilitate public benefit.

• Living at the Edge of Experience

  • Inspired by Josh Waitzkin’s analogy: live as if "strapped to the front of the train," directly experiencing life as it unfolds.

  "My life's an evolution. I'm not interested in being my 49 year old self. ... I think now I just like, I want to be my 50 year old self."
  — Andrew Huberman, [84:34]

Notable Quotes & Memorable Moments

• "You want your morning cortisol really high. This is what no one will tell you."
  — Andrew Huberman, [00:49]

• "If you miss that window... and then you get bright light in your eyes, the problem is you no longer increase cortisol, you actually suppress cortisol."
  — Andrew Huberman, [05:53]

• "The most important aspect of our biology, full stop."
  — Andrew Huberman, [26:43]

• "The brightest mornings and days and the darker your nights, the more mentally healthy you are."
  — Andrew Huberman, [24:36]

• "I started breaking them [licorice root capsules] in half and putting half in my morning mate. Oh, man... it's improved my energy, my sleep."
  — Andrew Huberman, [07:53]

• "The real information about whether or not that's a great mate... is their smell. ... I'm convinced it's through the nose, 100% convinced."
  — Andrew Huberman, [50:09]

Timestamps for Key Segments

• Cortisol & Sunlight 101: [00:02–09:45]
• Cortisol Curve and Immune Health: [04:00–07:50]
• Supplements & Sunlight Timing: [07:50–09:45]
• Evening Light, Melatonin, and Opposing Signals: [09:45–13:40]
• Sunlight's Primacy (vs. Technology/Hacks): [21:04–26:47]
• Sunglasses, Sunscreen, and their Effects: [26:47–34:30]
• Chemical Sensitivities and Personal Care Products: [34:30–36:06]
• Olfactory System, Gut Feeling, and Relationship Chemistry: [36:06–51:54]
• Firelight, Moonlight, and the Threat of Screens: [63:16–66:33]
• Personal Reflections on Turning 50 and Loss: [53:29–77:02]
• Evolution of Huberman Lab Podcast: [77:08–84:37]
• Existential Reflections: Time and Experience: [84:34–88:21]

Tone

• Warm, accessible, enthusiastic, and reflective.
  Huberman brings nuanced science down-to-earth, candidly sharing stories of loss and growth. Rubin’s gentle curiosity and resonance keeps the atmosphere intimate and grounded.

Takeaways for Listeners

• Morning sunlight is non-negotiable for circadian health.
• Respect your body’s primitive sensory systems—smell, intuition, light sensitivity.
• Many “modern” practices (e.g., chemical sunscreens, artificial fragrance, late-night screens) disrupt ancient biological wiring.
• Personal legacy, creativity, and well-being are inexorably linked to daily biological rhythms and genuine relationships.
• Evolution and self-renewal are lifelong processes—embrace "new stories."

This episode is a masterclass in biological self-alignment, told with the wisdom of lived experience and the humility of ongoing learning.