Huberman LabUsing Cortisol & Adrenaline to Boost Our Energy & Immune System Function
CHAPTERS
- 0:00 – 13:40
Intro, Sponsors, and Episode Overview
Huberman introduces the podcast, thanks sponsors, and outlines that this episode will extend his hormone series by focusing on cortisol and epinephrine, especially how they impact energy, stress, sleep, immunity, and learning.
- •Huberman Lab’s mission is to provide zero‑cost, science‑based tools to the public.
- •Sponsors: InsideTracker (blood/DNA analytics), Athletic Greens, and Headspace.
- •This is an extra, fifth episode in the hormones series, focusing on cortisol and epinephrine/adrenaline.
- •Topics preview: stress and energy regulation, sleep, immune enhancement, learning, nootropics, caffeine’s impact on brain wiring, and comfort foods.
- 13:40 – 25:00
Housekeeping: Fasting, Stomach Growling, and Growth Hormone from Heat
Before diving into cortisol and epinephrine, Huberman revisits listener questions from previous episodes about intermittent fasting, the biology of stomach growling, and alternative ways to boost growth hormone via heat.
- •Fasting increases growth hormone via ghrelin binding to the growth hormone–releasing hormone receptor, roughly doubling daytime GH.
- •Stomach ‘growling’ is due to smooth muscle contractions that tumble an empty stomach, not fluid noise; better chewing reduces loud grumbles.
- •Hot baths can increase growth hormone but carry burn risks; dry saunas at high temperatures are safer and far more potent.
- •Caution urged when experimenting with extreme heat or cold; always consult a doctor.
- 25:00 – 32:40
Cortisol and Epinephrine: Foundations and Reframing Stress
Huberman explains what cortisol and epinephrine are, how they’re produced, and why they should be reframed as essential energy and learning hormones rather than purely as 'stress hormones.'
- •Cortisol is a steroid hormone derived from cholesterol, competing with sex hormones (estrogen, testosterone) for that precursor.
- •Chronic stress diverts cholesterol toward cortisol production, potentially lowering sex steroids.
- •Epinephrine (adrenaline) is produced in the body and brain; it’s central to immunity, memory, and neuroplasticity, not just fight‑or‑flight.
- •The key issues are magnitude, duration, and timing of hormone release—not whether cortisol and adrenaline are 'good' or 'bad.'
- 32:40 – 41:00
Cortisol and Epinephrine 101: Mechanisms and Daily Stress Spikes
A quick physiology tutorial covers how the brain–pituitary–adrenal axis generates cortisol and how different pathways release epinephrine in body and brain. Huberman emphasizes that daily life events create inevitable hormone spikes that are healthy if they’re brief.
- •Cortisol pathway: CRH (brain) → ACTH (pituitary) → cortisol (adrenals); it promotes movement, wakefulness, and suppressed appetite initially.
- •Epinephrine pathway: sympathetic chain and adrenals flood body; locus coeruleus releases epinephrine in brain for alertness.
- •Common daily stressors (traffic, emails) cause transient cortisol/epinephrine blips that are adaptive when short‑lived.
- •Cortisol also binds receptors in amygdala and learning centers, linking stress to neuroplasticity and memory.
- 41:00 – 53:00
Tool 1: Morning Light to Properly Time Cortisol and Support Mood
Huberman lays out a concrete protocol for using outdoor light early in the day to control when the daily cortisol peak occurs, improving energy, sleep, and mental health.
- •Every 24 hours, cortisol must spike to wake you; timing this spike to early morning is critical.
- •Protocol: go outside within ~30 minutes of waking; no sunglasses; look toward but not directly at the sun.
- •On bright days ~5–10 minutes is sufficient; on overcast days ~20–30 minutes; indoor lighting is far too dim for effective timing.
- •Properly timed cortisol improves focus, learning, sleep onset, and reduces risk of late‑evening cortisol surges associated with depression/anxiety.
- 53:00 – 1:03:40
Deliberate Stressors: Cold, Breathing, and Intense Exercise
The episode shifts to practical ways of intentionally increasing epinephrine and cortisol—cold exposure, cyclic breathing, and high‑intensity exercise—while exploring their shared mechanism as 'stressors' and how mindset modulates but does not erase the biological response.
- •Ice baths, cold showers, HIIT, heavy lifting, hot yoga, and deep cyclical breathing all raise epinephrine and cortisol.
- •The body does not biologically distinguish between a stressful text and a cold plunge; they’re all 'stress' at the hormone level.
- •Cognitive reframing ('I like this') cannot prevent adrenaline release but can increase dopamine, which supports greater endurance and perceived control.
- •These tools can be scheduled deliberately to boost daytime energy in people with low baseline alertness.
- 1:03:40 – 1:10:40
Protocol: Cyclic Hyperventilation (Wim Hof/Tummo) and Safety
Huberman describes a specific breathing protocol that sharply elevates adrenaline and body heat, then explains how to use such protocols for energy, stress resilience, and as a complement to other stressors like cold exposure.
- •Breathing pattern: 25–30 rapid deep inhales and exhales, then an exhale hold for 15–30 seconds; repeat 3–4 rounds, optionally ending with an inhale hold.
- •This induces strong bodily agitation and warmth via adrenaline release, not 'inner heat' in a mystical sense.
- •Safety: never perform near water, while driving, or with heavy machinery; people have died mixing breath holds with water.
- •These sessions can be done 2–3 times per week to build stress resilience and increase accessible energy.
- 1:10:40 – 1:22:40
Key Mechanism: Separating Body Adrenaline from Brain Adrenaline
A crucial mechanistic distinction is made: cortisol crosses into the brain, but epinephrine released from the body does not. This allows a state of high bodily readiness with a calm mind, which Huberman argues is trainable and highly adaptive.
- •Cortisol crosses the blood–brain barrier and influences threat detection and mood; epinephrine from the body does not.
- •The brain releases its own epinephrine from locus coeruleus; this drives mental agitation and racing thoughts.
- •Deliberate practices (e.g., cold showers) are an opportunity to keep the mind calm while the body is highly activated.
- •The training goal is to decouple peripheral adrenaline surges from excessive brainstem epinephrine release.
- 1:22:40 – 1:42:20
Epinephrine and Immunity: From Classic Stress Studies to Wim Hof
Huberman reviews foundational animal and human work by McEwen and others showing that short‑term stress enhances immunity, then details a modern human study using Wim Hof breathing plus E. coli injection to demonstrate voluntary immune modulation.
- •Short bouts of stress (1–4 days) before or during infection improve immune responses; prolonged stress impairs them.
- •Adrenalectomy (removal of adrenals) abolishes this immune boost, proving that body‑generated adrenaline drives the effect.
- •PNAS 2014 Kox et al. study: volunteers trained in Wim Hof breathing and cold could attenuate fever, vomiting, and inflammatory responses after E. coli injection.
- •Cytokines like IL‑6 decreased, IL‑10 increased; conclusion: humans can voluntarily up‑regulate immune defenses by spiking adrenaline.
- 1:42:20 – 1:54:20
Leveraging Epinephrine and Cortisol for Learning and Memory
The discussion turns to how stress hormones govern learning and memory, emphasizing that epinephrine after an experience is particularly important for consolidating what came before, and outlining a full learning protocol.
- •Moderate elevations in epinephrine improve performance; very high mental stress can impair it by shifting attention to bodily sensations.
- •Epinephrine spikes tag preceding events as important, leading to strong memories of what happened before a shocking or emotional incident.
- •Optimal learning stack: ~90 minutes focused work → adrenaline‑raising bout (cold, breathing, or intense exercise) → NSDR → sleep.
- •Caffeine might be best taken later in the learning session to augment consolidation rather than front‑loading stimulation.
- 1:54:20 – 2:06:40
Caffeine, Brain Connectivity, and Nootropics
Huberman examines recent research showing habitual coffee drinkers have altered anxiety‑related brain connectivity, then reframes nootropics by explaining that many work chiefly through raising blood glucose and catecholamines, not special cognitive pathways.
- •Magalhaes et al. 2021: habitual coffee drinkers show strengthened connectivity among anxiety‑related brain regions even when not acutely caffeinated.
- •This may be problematic for those prone to anxiety or panic, and suggests timing and dose of caffeine matter.
- •Many 'smart drugs' (racetams, amphetamine, cocaine) enhance learning mainly by elevating blood glucose and catecholamines.
- •A second class of nootropics works via cholinergic mechanisms (e.g., choline, phosphatidylserine).
- 2:06:40 – 2:20:20
Comfort Foods, Chronic Stress, and the Cortisol Feedback Flip
Huberman explains why chronic stress drives cravings for high‑fat, high‑sugar 'comfort foods,' detailing how the normal negative feedback loop of cortisol can flip into a positive loop, amplifying stress and metabolic dysfunction.
- •Under usual conditions, high cortisol shuts down CRH and ACTH in a negative feedback loop, reducing further cortisol release.
- •With chronic stress (~4–7+ days), the system can flip: high glucocorticoids cause more CRH/ACTH release, creating a positive feedback loop.
- •Mary Dallman’s work shows chronic stress drives strong preferences for sugar and fat, which can lead to weight gain and type 2 diabetes.
- •Body fat is neurally innervated and becomes part of the stress‑signaling loop, reinforcing anxiety and comfort‑food seeking.
- 2:20:20 – 2:28:20
Gray Hair, Aging, and Stress; Importance of Ongoing Stress Regulation
Beyond metabolic and mood consequences, Huberman describes how chronic activation of the sympathetic nervous system depletes melanocyte stem cells in hair follicles, accelerating graying, and reiterates the protective role of sunlight and stress‑reduction practices.
- •Sympathetic activation can increase local peroxide and deplete melanocyte stem cells, causing hair to go gray faster.
- •Zhang et al. 2020 in Nature demonstrated stress‑induced graying via melanocyte stem cell depletion.
- •Sunlight stimulates melanocytes in both skin and hair; sufficient light plus stress management can partially counter graying pressure.
- •Regular practices like NSDR, meditation, massage, and vacations help prevent chronic stress from embedding biologically.
- 2:28:20 – 2:43:00
Defining Chronic Stress and Reducing Cortisol with Supplements
Huberman operationalizes chronic stress as stress persisting beyond a couple of days without restorative sleep, then moves into evidence‑backed supplements like ashwagandha and apigenin to lower cortisol and anxiety, with practical timing recommendations.
- •Any stress lasting more than a day or two and impairing sleep or recovery is moving toward chronic territory.
- •Ashwagandha has strong human data (multiple independent studies) showing ~14.5–27.9% reductions in cortisol and significant anxiolytic effects.
- •Downstream benefits include lowered CRP, heart rate, palpitations, improved thyroid hormone (T3/T4), and reduced OCD symptoms.
- •Apigenin (from chamomile) has mild anti‑estrogenic, anxiolytic, and cortisol‑lowering effects and is useful before bed for sleep.
- •Both are best taken later in the day to avoid blunting the morning energy‑promoting cortisol peak.
- 2:43:00 – 2:49:20
Hidden Cortisol Booster: Licorice, and Strategic Use Cases
A less obvious factor in cortisol regulation is black licorice, which contains glycyrrhizin; Huberman explains its impact on cortisol, blood pressure, and sex hormones, and when it might or might not be advisable.
- •Black licorice increases cortisol, raises blood pressure, and can lower testosterone and estrogen.
- •These effects have been observed across genders and ages in multiple human studies.
- •Licorice is therefore a poor choice for chronically stressed individuals or those seeking to optimize sex hormones.
- •In theory, it might be used strategically (with caution) to aid alertness when shifting time zones, but risks and timing must be carefully managed.
- 2:49:20 – 3:07:00
Fasting, Meal Timing, and Neural vs. Caloric Energy
Huberman distinguishes between energy from food and 'neural energy' driven by neurotransmitters and hormones, then outlines how fasting schedules impact epinephrine and cortisol, with caveats based on one’s stress load.
- •Energy is not only from calories; neural energy arises from epinephrine, cortisol, and other neuromodulators.
- •Any fasting window of ~4–6 waking hours raises epinephrine and cortisol; longer fasts can be leveraged for alertness if overall stress is low.
- •Huberman’s routine: morning light, delayed caffeine (90–120 minutes after waking), first low‑carb meal around midday, which keeps epinephrine relatively high.
- •Carbohydrate intake dampens cortisol and epinephrine; heavy carb meals are calming but can reduce alertness.
- •When life stress is high, layering long fasts or intense cold/exercise can push you into harmful chronic stress; in low‑stress times, these can be useful tools for energy.
- 3:07:00
Training Stress Control: Calm Mind, Activated Body, and Wrap‑Up
In closing, Huberman synthesizes the episode: the power of deliberately raising and then shutting off cortisol and adrenaline, how to gauge whether you need more or less stress chemistry, and the importance of practicing dissociation between body activation and mental agitation.
- •Short‑term, well‑timed spikes in cortisol and epinephrine improve energy, immunity, and learning; chronic elevation damages metabolism, mood, sleep, and appearance.
- •Self‑assessment: are you under‑activated (low energy) or over‑activated (burnt out)? That determines whether to add or remove stressors like cold, HIIT, and fasting.
- •Behavior, nutrition, supplements, and (if necessary) prescription drugs are levers to modulate these hormones.
- •A core training goal is the ability to remain mentally calm when adrenaline surges—preventing destructive reactions in real‑world stressful moments.
- •He encourages listeners to apply a learning protocol (study → adrenaline spike → NSDR → sleep) to this very episode and invites engagement via subscriptions, comments, and social platforms.
