If you have struggled with low mood, anxiety, or a kind of bone-deep fatigue that sleep does not fix, there is a reasonable chance someone has checked your cortisol. There is an even better chance they checked it exactly once, in the morning, as a single number on a blood panel — and then told you it was normal.
I want to walk you through why that one number, while not wrong, is often not enough. Your stress-response system does not work in single numbers. It works in rhythms. And when we only look at one point on a curve, we can miss the part of the story that actually connects to how you feel.
Your stress system runs on a daily clock
The medical name for your central stress-response system is the hypothalamic-pituitary-adrenal axis — the HPA axis. Think of it as a conversation between your brain and your adrenal glands. The brain senses a demand, sends a signal down the line, and the adrenals release cortisol, the body’s main stress hormone.
Cortisol is not the villain it is sometimes made out to be. You need it. It helps you wake up, mobilize energy, regulate inflammation, and meet the day. What matters for your mood is not simply how much cortisol you have, but when you have it.
In a healthy pattern, cortisol follows a daily rhythm. It is low overnight, rises sharply in the first 30 to 45 minutes after you wake — a feature researchers call the cortisol awakening response, or CAR — and then tapers down across the day to its lowest point at night [1]. That arc is the signature of a stress system doing its job: a strong “go” signal in the morning, a gentle wind-down by bedtime.
When that arc flattens, spikes, or inverts, the total amount of cortisol can still look perfectly ordinary on a single draw. The shape is what has changed.
Why one morning cortisol draw is a snapshot of a moving picture
Imagine trying to understand someone’s whole day from a single photograph taken at 8 a.m. You would learn something — but you would have no idea what happened at noon, at dinner, or at midnight.
A single morning serum cortisol is that photograph. It captures one moment near the top of the curve. It cannot tell you whether the morning rise was robust or blunted, whether cortisol fell appropriately by evening or stayed stubbornly elevated when you were trying to sleep, or whether the whole rhythm had simply gone flat.
This is why two people can both have a “normal” morning cortisol and feel completely different. One has a healthy rhythm. The other has a dysregulated one that the snapshot never captured. If your mood symptoms have never made sense against your lab results, this gap between a single value and a daily pattern is one of the first places I look.
What the research actually shows — and where it argues with itself
Here is where I want to be honest with you, because the science on cortisol and mood is genuinely unsettled, and you deserve the real picture rather than a tidy slogan.
It would be easy to write “high cortisol causes depression.” It would also be wrong. The literature is far more interesting than that.
Some studies do find elevated cortisol in people experiencing depression. In one comparison of younger and older adults, younger adults with higher depression scores showed higher overall cortisol and a larger awakening response [1]. A meta-analysis of children whose parents have a mood disorder — a group at high risk — found modestly higher daily cortisol levels on average, though the authors also flagged signs of publication bias in the awakening-response studies, which is a researcher’s way of saying the effect may be smaller than it first appears [2].
Other work points in different directions entirely. A large study of military veterans found that major depression could be characterized by low cortisol as well as high — not a single direction at all [3]. And a careful study asking whether the daily cortisol rhythm tracks anxiety and depression found that it largely did not. Instead, a blunted awakening response and a flat daily slope lined up with a specific symptom dimension the researchers summarized as “lack of energy” — the feeling that everything takes enormous effort [4]. That finding is worth sitting with, because “everything takes effort” is exactly the complaint I hear from so many people who have been told their labs are fine.
Then there is the question of whether fixing the symptoms fixes the hormones. You might assume that if someone’s depression improves, their stress hormones should normalize too. One study of an internet-based treatment for depression tested precisely this — and found that improvement in depression scores did not correspond to changes in cortisol [5]. The symptoms got better; the hormone pattern did not necessarily follow.
So what do we actually have? Not a clean cause-and-effect arrow. We have a consistent signal that the dynamics of cortisol — its rhythm, its responsiveness — carry information that a single resting level does not. A recent meta-analysis captured this well, describing a pattern of “dynamic dysregulation” in which the awakening response is blunted and the daily slope flattens while total cortisol output stays unchanged [6]. In plain terms: the total can look normal while the rhythm is clearly off.
That is not a reason to dismiss cortisol. It is a reason to measure it properly.
The cortisol-to-DHEA story: balance, not just level
There is a second hormone in this conversation that rarely makes it onto a standard workup: DHEA.
DHEA (and its storage form, DHEA-S) comes from the same adrenal glands as cortisol, but it tends to play a balancing, restorative role against some of cortisol’s more catabolic, “breaking-down” effects. Because of that, the ratio of cortisol to DHEA can tell us something neither hormone tells us alone — a rough read on whether your stress system is tilted toward breakdown or recovery.
This is not a fringe idea. In people with treatment-resistant depression, both cortisol and the cortisol-to-DHEA ratio were found to be elevated compared with healthy controls, and the ratio stayed remarkably stable across the working day, which makes it an appealingly practical marker [7]. In adolescents experiencing a first episode of depression, a higher evening cortisol-to-DHEA ratio predicted which young people stayed depressed months later — when neither hormone on its own did [8]. And in a brain-imaging study, it was the cortisol-to-DHEA ratio, rather than cortisol by itself, that tracked with hippocampal volume, a region central to mood and memory — the authors described the ratio as a measure of “net steroid activity” [9].
The through-line across these studies is the same lesson as the rhythm: the relationship between hormones often carries more meaning than any single value. Balance, not just level.
What pattern-level testing adds
So if a one-time morning cortisol is an incomplete tool for mood work, what would a fuller picture involve?
Two things, mainly. The first is timing — collecting cortisol at several points across the day rather than one, so the actual shape of your rhythm becomes visible: the morning rise, the daytime descent, the bedtime low. The second is measuring metabolized cortisol — the breakdown products your body produces as it processes cortisol — which reflects your total daily cortisol production rather than only the free fraction floating in your blood at one instant. Add in DHEA, and you can also see the cortisol-to-DHEA balance.
This is the kind of information a urinary hormone assessment such as the DUTCH Plus is designed to provide: a multi-timepoint map of the rhythm, a read on total cortisol production through its metabolites, and the cortisol-to-DHEA relationship in one picture. I am not describing this to sell you a test. I am describing it because it answers a different question than a single blood draw answers. A snapshot asks, “How much cortisol is in your blood right now?” A pattern asks, “Is your stress system keeping a healthy daily rhythm?” For mood symptoms, the second question is usually the more useful one.
None of this replaces a conversation with your psychiatric or primary-care provider. It adds a layer of information that standard care often does not collect — and that, in my experience, can reframe a confusing picture.
“Wired and tired”: connecting the curve to how you feel
Patterns are abstract until they map onto a real day, so let me connect a few.
A flattened curve — not much of a morning rise, not much of an evening fall — often shows up as that “lack of energy” picture the research describes [4]: hard to get going in the morning, foggy through the day, a sense that ordinary tasks cost too much. A rhythm that stays elevated into the evening can feel like being “wired and tired” — exhausted but unable to settle, lying awake with a busy mind. These descriptions are not diagnoses, and the same feeling can have several different drivers. But when a rhythm pattern lines up with what you have been living, it can be a genuine relief — the first time the data has matched the experience.
That matching is the point. The goal is not to label you. It is to understand what your stress-response system is actually doing, so that the next steps are based on your biology rather than on guesswork.
What this does — and does not — mean for you
I want to be careful here, because this is the part where it would be easy to overpromise.
A dysregulated cortisol rhythm is not a diagnosis, and it is not destiny. Cortisol patterns are one input among many — sleep, blood sugar, thyroid function, inflammation, life circumstances, and medications all shape the same system. Testing the rhythm does not, by itself, fix anything, and no responsible reading of the current science would promise that adjusting cortisol will resolve a mood condition. The honest framing is humbler and, I think, more useful: assessing the pattern can reveal something a single number missed, and that revelation can change the questions worth asking next — with your prescribing provider, not instead of them.
If you have been told you are treatment-resistant, this is exactly the kind of information I would want before accepting that label. Sometimes the most powerful step is not trying one more thing, but looking more carefully at what has not yet been measured.
Curious what your own stress-hormone rhythm looks like? Understanding your HPA axis starts with a real conversation, not a single lab value. If you would like to explore what comprehensive assessment could reveal about your mood, you are welcome to book a free 15-minute discovery call — no pressure, just a place to start.
Frequently asked questions
Can a normal morning cortisol test still miss a problem?
Yes. A single morning cortisol captures one point near the top of your daily curve. It cannot show whether your cortisol rhythm flattens, stays elevated at night, or has a blunted awakening response. Research consistently finds that the dynamics of cortisol — its rhythm and responsiveness — carry information a single resting value does not [6].
What is the cortisol awakening response?
The cortisol awakening response (CAR) is the sharp rise in cortisol during the first 30 to 45 minutes after you wake up. It is considered a marker of how reactive and well-regulated your stress system is. A blunted or exaggerated awakening response has been studied in relation to mood and energy, though findings vary across populations [1][4].
Does high cortisol cause depression?
No — the science does not support that simple a claim. Some studies find elevated cortisol in depression, others find low cortisol, and at least one found that improving depression did not change cortisol at all [3][5]. Cortisol patterns are associated with mood and energy, but they are one contributing factor among many, not a single cause.
Why measure DHEA along with cortisol?
DHEA tends to balance some of cortisol’s breaking-down effects, so the cortisol-to-DHEA ratio can indicate whether your stress system is tilted toward strain or recovery. In several studies, this ratio carried information that cortisol alone did not — including predicting which depressed patients stayed depressed over time [7][8].
What is the DUTCH test, and how is it different from a blood cortisol test?
The DUTCH Plus is a urinary hormone assessment that measures cortisol at multiple points across the day, estimates total cortisol production through its breakdown products, and includes DHEA. Compared with a single blood draw, it shows the shape of your daily rhythm rather than one moment in it. It is an educational and assessment tool, not a treatment.
Should I stop or change my medication based on a cortisol test?
No. Never adjust psychiatric medication on your own. Hormone testing is information to bring to your prescribing provider, not a reason to make changes without them. The data can inform a conversation; it should never replace one.
The bottom line
Your stress-response system speaks in rhythms, not single numbers. A morning cortisol value can sit comfortably inside the normal range while the daily pattern that actually relates to your mood and energy has quietly lost its shape. The research is honest about its own uncertainty — cortisol is not a simple on-off switch for depression, and the relationship runs in more than one direction. But that uncertainty is precisely why the pattern matters more than the snapshot, and why the cortisol-to-DHEA balance can add a dimension that either hormone alone leaves out.
If you have done the work — therapy, medication, real effort — and still feel stuck, it is worth asking whether your stress-hormone rhythm has ever truly been looked at, rather than glanced at once. You are not a single data point, and you deserve an assessment that reflects that. The question I keep coming back to with the people I work with is the same one I would offer you: not “what is wrong with you,” but “what is actually driving this — and has anyone looked closely enough to find out?”
If that question resonates, a free discovery call is a low-stakes place to begin.
About the author
David Wiss, PhD, RDN, FMCP is the founder of FxMed Mental Health, a virtual functional medicine practice focused on complex, treatment-resistant mental health. With a doctorate in public health and a background as a registered dietitian nutritionist, David’s work centers on cross-system pattern recognition — connecting findings across the gut, hormones, nutrients, genetics, and inflammation to understand the biology beneath mental health symptoms. FxMed Mental Health coordinates with patients’ prescribing providers and does not replace psychiatric care.
Disclaimer
This article is for educational purposes only and does not constitute medical advice. It is not intended to diagnose, treat, cure, or prevent any condition. The hormone patterns and research discussed here describe general findings and do not predict any individual’s results or outcomes. Cortisol, DHEA, and HPA-axis testing are assessment tools, not treatments. Do not start, stop, or change any medication or supplement based on this article. Always consult your physician or qualified mental health provider about your individual situation, and never disregard or delay seeking professional advice because of something you have read here. If you are in crisis, contact your local emergency services or a crisis line immediately.
References
All references below were independently verified through PubMed prior to inclusion. According to PubMed:
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