Essentials: Boost Your Energy & Immune System with Cortisol & Adrenaline

In this Essentials segment, Andrew Huberman, a professor of neurobiology and ophthalmology at Stanford School of Medicine, revisits a past episode to distill what he calls the most potent and actionable science-based tools for mental health, physical health, and performance [s00003, s00004]. He states that the podcast is separate from his teaching and research roles at Stanford, and frames the episode as part of an effort to bring zero-cost-to-consumer information about science and science-related tools to the general public [s00005, s00006]. The central claim is narrow but strong: two hormones, cortisol and epinephrine (also called adrenaline), dominate the processes of having enough energy and having a healthy immune system [s00007, s00008, s00013].

The first move is definitional. Cortisol is a steroid hormone derived from cholesterol, in the same chemical family as estrogen and testosterone [s00015]. Cholesterol is described as a precursor molecule, the substrate from which hormones like testosterone and estrogen are made, and cortisol is presented as the competitive partner to estrogen and testosterone [s00016, s00017]. The practical consequence Huberman draws is that no matter how much cholesterol you eat or produce, whether the level is low or high, stress devotes more of that cholesterol to creating cortisol [s00018].

This leads to his key reframe: the word stress should not itself cause anxiety, because cortisol is genuinely needed [s00019]. It is important for immune system function, for memory, and for not getting depressed [s00022]. The caution is not against cortisol per se but against levels that are too high, or even normal levels elevated at the wrong time of day [s00021, s00023].

Cortisol is vital.

Epinephrine receives the same treatment. Although commonly imagined as the stress hormone behind anxiety and fight-or-flight, Huberman argues it is in fact the body's ally for immunity, protection from infection, remembering things, learning, and activating neuroplasticity [s00024, s00025, s00026].

epinephrine is your best friend when it comes to your immunity, when it comes to protecting you from infection

The synthesis is explicitly about dose and timing rather than moral valence. Once again, it is a question of how much and how long and the specific timing of release of cortisol and epinephrine, as opposed to the hormones being good or bad [s00028]. Regulated, they are terrific; misregulated, they are terrible, and the episode promises tools to regulate them better [s00029, s00030].

They're terrific when they're regulated.

Huberman compresses the cortisol axis into a short chain. The brain makes releasing hormones, in this case corticotropin-releasing hormone (CRH), produced by neurons [s00065]. CRH causes the pituitary, a gland sitting about an inch in front of the roof of the mouth in the base of the brain, to release ACTH [s00066]. ACTH then causes the adrenals, which sit above the kidneys in the lower back, to release cortisol [s00067]. He asks the listener to think about cortisol not as a stress hormone, but as a hormone of energy, one that creates a state in which you want to move, do not want to rest, and, at least at first, do not want to eat [s00067, s00068].

The adrenaline pathway is faster and more distributed. When the mind or body senses a stressor, a signal is sent to neurons in the middle of the body called the sympathetic chain ganglia, a name Huberman says does not necessarily matter [s00070, s00071]. They release norepinephrine very quickly, in a manner he compares to a sprinkler system hosing the body with epinephrine, which increases heart rate and breathing rate and increases the size of vessels and arteries delivering blood flow to vital organs [s00072, s00073, s00074, s00075]. Adrenaline is also released from the adrenals and from the locus coeruleus in the brain, creating alertness [s00076]. The net effect of the two hormones together is to increase energy [s00077].

It's almost like a, a sprinkler system that just hoses your body with epinephrine.

The first actionable protocol concerns timing. One way or another, every 24 hours you will get an increase in cortisol, whose job is to stimulate movement from sleep, presumably horizontal, into the day; the first tool is therefore to make sure the highest levels of cortisol occur first thing in the morning upon waking [s00078, s00079]. The recommended trigger is to get outside very soon after waking, within about 30 minutes, and view some sunlight, even if it is overcast, and without sunglasses [s00080, s00081]. Doing so early in the day is said to improve focus, energy levels, and learning throughout the day [s00082, s00083].