On cortisol, a wellness economy built on a hormone doing its ordinary job, and the one question the ads are engineered to keep you from asking.
There is a shelf now. You have seen it: in the chemist, in the wellness aisle, or more likely unspooling down your phone at eleven at night, when you should be asleep and your body should be quietly doing its filing. The gummies, the powders, the capsules, the calming lattes the colour of wet sand, every one of them promising to lower your cortisol. In roughly two years the word has been promoted from obscure adrenal secretion to the villain your phone holds personally responsible for your face. Cortisol face, cortisol belly, cortisol mocktails, and—a coinage I decline to define here on the grounds that I would like to keep the will to live—cortisolmaxxing. An entire economy of dread has assembled itself around a single hormone, and it is not a small one. The adaptogen trade alone runs to billions, with the forecasts climbing happily for another decade, because dread, unlike almost every other product, never has a bad quarter.
So let me ask the question the ads are engineered, with real care, to keep you from asking. Not, is my cortisol high? The better one, the question with somebody’s mortgage riding on your never quite reaching it: who gets paid when you believe it is?
What cortisol is actually up to
Here is the inconvenient fact about cortisol, from the point of view of anyone hoping to sell you a cure for it: it will not hold still long enough to be a villain. It is not a sludge that builds up. It does not pool in you over a hard fortnight like silt in a tank, waiting for a gummy to arrive and pull the plug. It moves fast. Your body clears half of what is circulating in an hour or so, and across a day the whole supply runs on a tide, high in the hour you wake and tapering to almost nothing by the time you are lying in the dark negotiating with the ceiling. Riding on that tide are smaller pulses, one every hour or two, all day, whether your life is on fire or entirely fine.
Which means a single cortisol reading tells you about as much as a single frame tells you about a film. Your morning spit test has caught the hormone mid-stride, frozen it, and now reads the one motionless syllable back to you like a ransom note—and mid-stride is exactly where a healthy body keeps it, dozens of times a day, every day, for the whole of your life. Cortisol going up is not the malfunction. Cortisol going up is the hormone clocking on: when you wake, when you eat, when you climb a hill, when you catch a cold, when somebody opens with “we need to talk” in that particular voice that removes the floor.
The science the shelf would rather you skipped
If chronic stress reliably cranked cortisol up and left it jammed there, the gummies would at least be firing at a real target and merely missing it. But that is not what the research found, and it stopped finding it a remarkably long time ago.
In 2007, three researchers—Miller, Chen and Zhou—waded through the entire contradictory literature on chronic stress and cortisol, the studies swearing it goes up and the studies swearing it goes down, and worked out why the argument would not end (Miller et al., 2007). Timing, mostly. Cortisol climbs when a stressor first lands, then, as the months grind on with no let-up, it slopes the other way. Long, uncontrollable, grinding stress does not hand you a dramatic high number. It hands you a flat one: “a high, flat diurnal profile of cortisol secretion,” in their words, a rhythm that has lost its shape. The strong morning rise goes soft. The deep night-time trough fills in. The gap between your peak and your floor, the daily contrast that makes a morning feel unlike a midnight, narrows until the whole system idles on one grey note from dawn to dark.
That was 2007. Which means the cortisol-panic industry is selling frantic cures for a model the science quietly buried while most of us were still learning to text.
For a lot of us, it runs the other way
If you have read me before, you will know the shape of this already. It is the load, not the last straw, turning up in the bloodwork: the running tab a system runs up when it has been adapting for too long with too little quiet in between to reset. And for one particular group of people, the cortisol story does not merely soften under that load. It flips.
Rachel Yehuda spent decades documenting it. People carrying long-term PTSD—combat veterans, Holocaust survivors, survivors of sustained abuse, people who spent a childhood braced for the next bad thing—tend to run lower resting cortisol than people without it, not higher (Yehuda et al., 1995). The finding has sat in the American Journal of Psychiatry since the mid-nineties, quietly contradicting every reel on your feed. The mechanism is not exhausted, wrung-out adrenals. It looks more like a feedback loop that has become too competent, shutting the alarm off so briskly and so completely that it can barely raise its voice when something finally deserves one.
The childhood research walks in from the other side and arrives at the same house. A 2022 meta-analysis pooling 83 studies found that the more adversity a person hauled out of childhood, the more blunted their cortisol response to stress became in adulthood: the alarm turned down at the source, and turned down further the more there had been to survive (Brindle et al., 2022). An earlier meta-analysis had already found the same flattening (Bunea et al., 2017).
Now hold that against the shelf. There is a large, real group of people walking around with an alarm dialled down almost to silence, carrying the flat, grey, bone-level exhaustion that anyone who has survived a great deal will recognise on sight, and the entire wellness economy has bustled over to sell them something to turn that alarm down further. It is a fire blanket, at a brisk markup, for a house whose fire went out years ago and left the rooms cold. Not merely useless. Confidently, expensively aimed at the exact opposite of the problem, for ninety-nine dollars plus postage.
Even the flagship doesn’t say what they say it says
To be fair to the industry, and being fair to it sharpens the point rather than blunting it, its best-dressed product has real evidence underneath it. Ashwagandha, the most heavily marketed adaptogen on the whole shelf, has been through proper randomised trials, several of them, with meta-analyses stacked on top, and it does lower measured cortisol against placebo. That is a genuine result and I won’t pretend otherwise.
Here is the part that rarely makes the caption. Whether it makes anyone actually feel less stressed is where the evidence turns into a pub argument. Some reviews find people rating themselves calmer; at least one careful 2025 meta-analysis found the cortisol number performing a graceful swan-dive while the perceived-stress score stayed at the edge of the pool, fully clothed, feeling precisely as knackered as before (Albalawi, 2025). The lab value moved. The person did not.
That gap is the whole trick in miniature. If a hormone reading can fall by a third while the human wearing it feels no better, then the reading was never the thing hurting them. It was a proxy: a tidy, sellable number standing in for all the things that show up on no panel and cannot be couriered to your door—capacity, rest, recovery, and a life that has finally stopped asking more of you than you have to give.
The question worth asking instead
None of this needs a spit kit, and it very much does not need a subscription. The thing worth your attention was never the height of the number. It is the shape of the day. Does your system still lift when the morning asks it to, and can it come back down once the demand has passed? Can it sound the alarm and then, the harder trick by far, switch it off again? That capacity—up, and then back down again—is far nearer to what “regulation” actually means than any figure a forty-dollar kit will read you off a strip of paper.
I know a fair bit about this from the inside, and not from a lab. I spent the better part of six decades with a nervous system stuck in a middle gear it could not climb out of, braced against a world that never quite made sense, the alarm neither properly on nor properly off, just endlessly, greyly humming. What eventually shifted it was not a gummy, a mocktail, or a morning routine built on lemon water and self-belief. It was taking an entire life apart and rebuilding it around the problem until the emergency was finally allowed to end: a quieter country, softer light, the financial terror lifted at last, a rhythm my body could feel its way back into. The shelf cannot sell you that. Which is the whole reason the shelf would so much rather you kept staring at the number.
Because cortisol was never the enemy. It is part of what gets you out of bed, part of what carries you through a real threat, part of what your immune system leans on when you are properly ill, part of the plain machinery of being alive. The trouble, when there is trouble, is a rhythm that has lost its shape: a rise that will not come, a fall that will not finish, an alarm stuck too loud or—far more often than the ads will ever admit—gone quiet altogether. Not one of those is cured by being frightened of a hormone. And the fright, it turns out, was always the product. The cortisol was only ever the packaging.
With thanks to Karla Kösl in Poland, who pointed me toward the piece that set this off, and to Teresa Trieb, for her sheBREATH essay on the cortisol industry
References
Albalawi, A. A. (2025). Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress—A systematic review and meta-analysis. Nutrition and Health. Advance online publication. https://doi.org/10.1177/02601060251363647
Brindle, R. C., Pearson, A., & Ginty, A. T. (2022). Adverse childhood experiences (ACEs) relate to blunted cardiovascular and cortisol reactivity to acute laboratory stress: A systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews, 134, 104530. https://doi.org/10.1016/j.neubiorev.2022.104530
Bunea, I. M., Szentágotai-Tătar, A., & Miu, A. C. (2017). Early-life adversity and cortisol response to social stress: A meta-analysis. Translational Psychiatry, 7(12), 1274. https://doi.org/10.1038/s41398-017-0032-3
Miller, G. E., Chen, E., & Zhou, E. S. (2007). If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans. Psychological Bulletin, 133(1), 25–45. https://doi.org/10.1037/0033-2909.133.1.25
Yehuda, R., Kahana, B., Binder-Brynes, K., Southwick, S. M., Mason, J. W., & Giller, E. L. (1995). Low urinary cortisol excretion in Holocaust survivors with posttraumatic stress disorder. American Journal of Psychiatry, 152(7), 982–986. https://doi.org/10.1176/ajp.152.7.982
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