Cortisol Pattern Interpreter

Enter your cortisol test results to analyze your diurnal curve. Supports 4-point salivary cortisol panels and standard AM/PM serum tests. Pattern recognition identifies common HPA axis disruptions.

Reference Ranges — Salivary Cortisol

Morning (6–8 AM)100 – 750 ng/dL
Midday (12–1 PM)40 – 450 ng/dL
Afternoon (4–5 PM)20 – 200 ng/dL
Evening (10–11 PM)10 – 100 ng/dL

Ranges are approximate and vary by laboratory. Salivary values measure free cortisol; serum values include protein-bound cortisol. Always compare against your lab's own reference intervals.

The Cortisol Curve: Why Timing Matters

Cortisol follows a pronounced circadian rhythm governed by the HPA (hypothalamic-pituitary-adrenal) axis. Levels peak sharply within 30–45 minutes of waking — the cortisol awakening response (CAR) — then decline steadily throughout the day, reaching their lowest point around midnight. This predictable arc is essential for energy regulation, immune function, blood sugar control, and sleep architecture.

Why a single AM draw isn't enough: A morning blood cortisol can look normal even when the diurnal rhythm is disrupted. A flat curve — where evening cortisol is nearly as high as morning — can produce normal-looking individual values while indicating chronic stress dysregulation. Four-point salivary testing captures the full arc.

What disrupts the rhythm: Chronic psychological stress, poor sleep, irregular light exposure, shift work, alcohol, and certain medications (corticosteroids, oral contraceptives) can all blunt or invert the diurnal curve. Restoring the rhythm often requires addressing root causes rather than supplementing cortisol directly.

Adrenal Fatigue: What Science Actually Says

"Adrenal fatigue" is not a recognized medical diagnosis. True adrenal insufficiency (Addison's disease) is a serious and relatively rare condition in which the adrenal glands cannot produce sufficient cortisol, confirmed by ACTH stimulation testing — not by low-normal salivary readings alone.

What is real: HPA axis dysregulation absolutely exists. Chronic stress can alter the sensitivity of cortisol receptors and blunt the awakening response, producing fatigue, brain fog, and poor stress resilience even when absolute cortisol levels appear normal. This is a regulatory problem, not a production problem — and it responds to sleep optimization, stress reduction, and circadian rhythm work, not adrenal supplements.

If your pattern suggests significant dysregulation, pursue formal evaluation with an endocrinologist rather than self-treating with over-the-counter cortisol modulators.

Frequently Asked Questions

What is a normal cortisol curve?
Cortisol should peak in the morning (6-8 AM), at 2-3x the evening level, then decline progressively through the day. The lowest point is around midnight.
What does a flat cortisol curve mean?
Morning and evening cortisol levels are similar, with an AM/PM ratio below 2. This pattern is associated with chronic stress, burnout, disrupted sleep, and HPA axis dysregulation.
Is adrenal fatigue real?
"Adrenal fatigue" is not a recognized medical diagnosis. However, HPA axis dysregulation — where the brain-adrenal feedback loop produces abnormal cortisol patterns under chronic stress — is well-documented in research.
Which cortisol test is more accurate, saliva or blood?
Salivary cortisol measures free (bioactive) cortisol and allows 4-point home collection. Blood measures total cortisol and is better for diagnosing Cushing syndrome or Addison disease. They answer different questions.
What affects cortisol levels besides stress?
Sleep deprivation, shift work, alcohol, intense exercise, medications (prednisone, oral contraceptives), caffeine, and eating patterns all influence cortisol. Late-night eating and blue light exposure can elevate evening cortisol.

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This tool is for informational purposes only and does not constitute medical advice. Cortisol patterns vary significantly between individuals and laboratories. Consult an endocrinologist for persistent abnormalities, significant symptoms, or before making any changes to treatment. Do not use this tool to self-diagnose or self-treat adrenal conditions.