Using Cortisol & Adrenaline to Boost Our Energy & Immune System Function

High-Level Overview

In this Essentials episode, Andrew Huberman makes the case that cortisol and epinephrine (adrenaline), usually cast as villains, are actually the two hormones that most shape how much energy we have and how well our immune system works. The problem is never the hormones themselves but their amount, duration and timing: they are terrific when regulated and harmful when misregulated. He walks through the basic biology of each, then offers concrete tools, from morning sunlight to ice baths, breathing and meal timing, to raise these hormones at the right times and shut them off when needed.

The tone is practical and upbeat, with Huberman reframing stress as something you can learn to use rather than fear, and even briefly demonstrating a breathing protocol. The conversation moves from mechanism to daily protocols, then to the surprising science that short bursts of adrenaline can blunt the effects of infection, and finally to the costs of chronic stress and ways to lower cortisol.

The Discussion Explores:

• Cortisol and epinephrine as hormones of energy, and how and where they are released
• Timing the daily cortisol peak with morning sunlight, with specific durations by cloud cover
• Why brief daytime stress supports learning and neuroplasticity
• Deliberate stressors (cold, cyclic breathing, high-intensity exercise) as energy and resilience tools
• Training a calm mind in an alert body, and why that matters mechanistically
• Research showing short-term adrenaline boosts immune defense, including a 2014 E. coli study
• The harms of chronic stress: a runaway feedback loop, comfort-food cravings and gray hair
• Lowering cortisol with ashwagandha and apigenin, and using meal timing and fasting to shape energy

Deep Dive into Main Ideas

What Cortisol and Epinephrine Actually Are

Cortisol is a steroid hormone made from cholesterol, like estrogen and testosterone, and it competes with them for that raw material: when you are stressed, more cholesterol is diverted toward cortisol. The release chain starts in the brain with corticotropin-releasing hormone (CRH), which tells the pituitary to release ACTH, which in turn tells the adrenal glands above the kidneys to release cortisol. Huberman stresses that you need cortisol for immune function, memory and avoiding depression. He asks listeners to "think about cortisol not as a stress hormone, but as a hormone of energy", one that makes you want to move rather than rest or eat, at least at first.

Epinephrine is released fast, like a sprinkler system, from the sympathetic chain ganglia in the middle of the body, from the adrenals and, in the brain, from the locus coeruleus. It raises heart rate and breathing and increases blood flow to vital organs. Far from being only a source of anxiety, Huberman calls epinephrine your best friend for immunity, for learning and for activating neuroplasticity.

Timing Cortisol With Morning Sunlight

Everyone gets a daily cortisol rise that moves us from sleep into activity. The key tool is to make sure the highest level comes first thing in the morning. Within about 30 minutes of waking, get outside and view sunlight without sunglasses, even on overcast days. This improves focus, energy and learning throughout the day.

Huberman gives the numbers behind the advice. Morning sun with no clouds, while still low in the sky, is around 100,000 lux; a cloudy day is about 10,000 lux; very bright artificial light is about 1,000 lux; and ordinary room light is 100 to 200 lux. That is why indoor bulbs and your phone won't do the job. His guidelines: about 10 minutes outside on a clear day, 10 to 20 minutes with broken clouds, and roughly 30 minutes under dense overcast, done on a regular basis.

Daytime Stress, Learning and Deliberate Stressors

Throughout the day, life delivers stressors that cause blips in cortisol and epinephrine. These are fine, even useful, as long as they are brief. Cortisol binds to receptors in the amygdala and in areas involved in learning and memory, which is why Huberman says neuroplasticity is first stimulated by attention, focus and often a low-level state of agitation. Understanding this, he suggests, means you needn't be so troubled by small daily stress spikes.

You can also raise these hormones deliberately. An upsetting text, an ice bath, a cold shower, sprints, weightlifting or hot yoga all increase epinephrine and cortisol, and all raise energy and alertness. The body doesn't distinguish between them; it's all stress. Telling yourself you enjoy it doesn't change what the hormones do, but it does release dopamine, the precursor to epinephrine, giving you a bigger epinephrine response and a sense of control. His protocol for people with low daytime energy: with a doctor's clearance, pick one practice you can do consistently, whether daily or every third or fourth day, such as a cold shower or the cyclic breathing he demonstrates: 25 to 30 deep inhales and exhales, which make you feel warm and agitated because you are releasing adrenaline in the body and norepinephrine in the brain. These practices can either strengthen or deplete immunity depending on how often you use them.

Calm Mind, Alert Body

The one small but powerful adjustment Huberman recommends depends on a piece of mechanism. Cortisol crosses the blood-brain barrier; epinephrine does not, which is why it is released separately in body and brain. As he puts it, this means "the body can enter states of readiness and alertness while the mind remains calm."

So when you are in the cold shower or mid-workout, the goal is not to grind it out but to stay mentally calm, for example by emphasizing exhales, while your body stays highly alert. Mechanistically, you want adrenaline released from the adrenals without the same degree of release from the brainstem. Practiced regularly, this builds the ability to buffer stress from real life events, and in the period right after, your body is primed to resist infection.

Short-Term Stress Protects Against Infection

Classic work associated with Bruce McEwen at Rockefeller University exposed subjects to bacterial or viral infections while inducing stress, such as a mild foot shock or cold water. Rather than making things worse, brief bouts of stress increased immune function. Duration matters: stress that stays high too long hinders immunity, but for about one to four days it can protect you.

Huberman then highlights a human study by Kox and colleagues, published in PNAS in 2014, on voluntary activation of the sympathetic nervous system using Wim Hof-style breathing. Participants were injected with E. coli. Those who used the breathing to raise adrenaline had greatly reduced symptoms, such as fever and vomiting, in some cases eliminating them. He believes cold exposure or high-intensity exercise could work too. The main lesson, he says, is to learn to turn adrenaline and cortisol on and off; whether it's a cup of coffee and running up a hill five or six times or an ice bath, the specific protocol matters less than getting adrenaline into your system briefly.

The Cost of Chronic Stress

When cortisol and epinephrine stay high for too long, the immune system gets battered and cortisol-driven body fat builds up. Normally high glucocorticoid levels shut down the brain's releasing hormones through negative feedback. But stress lasting more than about four to seven days changes that loop so the brain and pituitary respond to high cortisol by releasing even more, turning it into a positive feedback cascade of stress begetting stress. In one animal study in which chronic stress was simulated by raising corticosterone, subjects increased their intake of sugar and fat, even eating lard, which led to problems like type 2 diabetes and adrenal dysfunction.

Huberman suggests watching your own appetite: short bouts of stress typically block hunger, while longer ones trigger cravings for sugary, fatty comfort food. And yes, "stress will make us go gray": activation of the sympathetic nervous system depletes the melanocytes in hair stem cells that give hair its pigment, on top of genetic aging.

Lowering Cortisol and Building a Foundation

The most powerful defense against chronic stress, Huberman says, is keeping light exposure, eating, exercise and sleep on a consistent schedule. For supplements, which each person must check for safety, he names ashwagandha, which in otherwise healthy but stressed humans reduces cortisol by 14.5 to 27.9 percent, and apigenin, found in chamomile, which he takes at 50 mg before bed; it calms the nervous system mainly via GABA and chloride channels and mildly lowers cortisol. He considers the pair the most potent non-prescription options for reducing cortisol, especially later in the day.

Meal timing also shapes neural energy. When blood glucose is low, such as after four to six hours without food, epinephrine and cortisol rise substantially. Many people benefit from circadian eating, eating roughly while the sun is up and stopping a couple of hours before sleep. Huberman describes his own routine: morning sunlight, water, caffeine delayed 90 minutes to two hours, and a first meal around 11:30 or noon, usually meat or fish with salad and no carbohydrates, which keeps his epinephrine fairly high. He frames fasting here as a way to bias the system toward healthy adrenaline and cortisol release without tipping into chronic stress, and recommends a practice every other or every third day of raising adrenaline in the body while keeping the mind calm.

Conclusion

Huberman's message is that cortisol and adrenaline are neither good nor bad; timing and duration decide their effect. Get cortisol peaking early with morning sunlight, welcome brief daily stress as fuel for focus and learning, and use deliberate stressors like cold, cyclic breathing or intense exercise to raise energy and even strengthen immune defenses, while practicing a calm mind inside an alert body. At the same time, recognize the signs of chronic stress, such as comfort-food cravings, and counter it with consistent schedules for light, food, exercise and sleep, sensible meal timing, and, if appropriate, supplements like ashwagandha and apigenin. As he puts it, "short term stress is healthy", and learning to switch these hormones on and off lets you control them rather than be controlled by them.

This is a summary of "Using Cortisol & Adrenaline to Boost Our Energy & Immune System Function" from Huberman Lab, giving you the GIST so you can decide if you want the REST. Listen to the full episode.