TL;DR: Cortisol between 7 and 9 am is 5–25 µg/dl (138–690 nmol/l), at night below 5 µg/dl. Highest value 30 minutes after waking (Cortisol Awakening Response). “Adrenal fatigue” is not a medical concept — what matters clinically is HPA axis dysregulation. For ashwagandha (Chandrasekhar 2012) and meditation (Goyal 2014) there are individual studies; the evidence is limited to mixed. Alcohol and excessive caffeine can raise cortisol — even though they feel relaxing.
This article is for information only and does not replace medical advice. Taking any supplement, its dose and any therapy need to be clarified with a physician; the article contains no recommendation to use anything. If you suspect Addison disease, Cushing syndrome or have markedly abnormal values, an endocrinologist is the right contact.
What Cortisol Actually Does
Cortisol is the body’s main stress hormone — and a vital daily rhythm-setter. The adrenal cortex produces it in pulses, controlled by the hypothalamus and pituitary. This chain is called the HPA axis: hypothalamus, pituitary, adrenal.
Cortisol has three main jobs at once. It mobilizes energy by raising blood glucose and free fatty acids. It dampens the immune system to prevent runaway inflammation. And it influences the sleep-wake cycle. Without cortisol the body does not get going in the morning — with persistently too much, sleep is often disturbed.
Acute vs. chronic. A short cortisol rise is eustress: alertness, focus, performance. A presentation, a sprint, an important conversation. Cortisol normalizes after 60 to 90 minutes. Chronically elevated cortisol, on the other hand, is distress and is associated with more belly fat, shallow sleep, more frequent infections and low mood.
An example of interpretation: a morning value of 28 µg/dl lies above the usual reference range. Whether it reflects HPA dysregulation, acute strain or a measurement artifact can only be clarified by a physician. In Lab2go you keep your cortisol history and note sleep quality and training load next to it — this helps to see values in context and to explain them at a medical appointment.
The Daily Rhythm: Why Timing Is Everything
Cortisol follows a tight circadian rhythm. If you ignore the clock, you measure noise.
Cortisol Awakening Response (CAR). 30 minutes after waking, cortisol rises 50 to 75 percent above the wake value. This peak prepares the body for the day. A flattened CAR is discussed as an early sign of burnout, depression or chronic stress. An exaggerated CAR suggests acute stress or anxiety.
Daily curve. After the peak, cortisol falls steadily. Midday 10 to 16 µg/dl, afternoon 5 to 10 µg/dl, evening below 5 µg/dl. At midnight it reaches its low point. In the second half of the night the rise begins again.
Measurement window. For a meaningful serum measurement the usual conditions are: 7 to 9 am, fasted, before training, before the first coffee. Any deviation can distort the result.
| Timing | Serum (µg/dl) | Serum (nmol/l) | Saliva (nmol/l) |
|---|---|---|---|
| Wake | 5–15 | 138–414 | 5–15 |
| 30 min after wake | 15–25 | 414–690 | 15–23 |
| Midday | 10–16 | 276–442 | 3–8 |
| Afternoon | 5–10 | 138–276 | 1–4 |
| Evening (10 pm) | <5 | <138 | <2 |
Testing Methods: Which Test When
The four common methods differ considerably in usefulness and cost.
Morning serum cortisol. Standard measurement at blood draw. Reference range 5–25 µg/dl (138–690 nmol/l) between 7 and 9 am. Fast and cheap (15–25 euros). Downside: the stress of the blood draw itself can raise the value. Only a single moment, no information about the daily curve.
4-point saliva day profile. Regarded as the reference for assessing the HPA axis. Samples are taken at home at waking, 30 minutes later, midday and evening. No blood draw stress. Cost: 40–80 euros. Suited to capturing CAR, rhythm and HPA dysregulation.
Hair cortisol. Measures average load over the last 3 months. Each centimeter of hair represents about 4 weeks. Useful for looking at long-term stress after break-ups, burnouts or long stress phases. Cost: 60–120 euros. Only available in specialized labs.
24-hour urine (free cortisol). Measures total excretion over 24 hours. Used less often today, but still relevant in suspected Cushing syndrome. Reference ranges depend on the laboratory.
For many questions the saliva day profile is the most informative choice. Morning serum cortisol alone is a snapshot that misses the rhythm.
Symptoms: Too Much vs. Too Little
Cortisol imbalance creates typical patterns. Symptoms overlap with other hormonal disorders — so they need to be combined with measurements and medical assessment.
Symptoms of chronically elevated cortisol:
- Trouble falling or staying asleep despite fatigue
- Belly fat accumulation (visceral fat)
- Sugar and salt cravings, especially in the evening
- Frequent infections — immune function is suppressed
- Fatigue despite 8 hours of sleep (“tired but wired”)
- High blood pressure, elevated resting heart rate
- Muscle loss despite training
- Irritability, concentration problems
Symptoms of chronically low cortisol:
- Severe morning fatigue, missing CAR peak
- Salt cravings (adrenal cortex makes less aldosterone)
- Dizziness on standing from low blood pressure
- Exercise intolerance — training leaves you flattened
- Low blood pressure
- Unexplained weight loss
- Skin hyperpigmentation (in Addison disease)
If morning cortisol is clearly below 3 µg/dl or above 30 µg/dl, workup with an endocrinologist is appropriate. Self-diagnosis as “adrenal fatigue” can delay the correct diagnosis and lead to real adrenal insufficiency being missed.
“Adrenal Fatigue”: Why the Term Is Wrong
Adrenal fatigue is a popular term from alternative medicine. The theory: chronic stress exhausts the adrenal glands until they can no longer produce cortisol. It sounds logical but is not physiologically valid.
What the science says. The Endocrine Society published a position paper in 2016: adrenal fatigue is not a recognized medical diagnosis. No reproducible measurements, no pathophysiology, no guidelines. Systematic reviews (Cadegiani 2016) found no evidence for the concept.
What is described instead. Chronic stress can lead to HPA axis dysregulation. Communication between hypothalamus, pituitary and adrenal becomes erratic. The adrenal glands keep functioning, but central control becomes irregular. Typical findings: flat CAR, elevated evening cortisol, disturbed sleep, low DHEA.
Why the distinction matters. “Adrenal fatigue” often leads to self-medication with hydrocortisone or adrenal extract. This can suppress your own cortisol production and cause withdrawal symptoms. Hydrocortisone is prescription-only and belongs under medical supervision. How an HPA dysregulation is interpreted is for the physician to decide; sleep, stress management and exercise are discussed in the literature as factors influencing the cortisol rhythm.
The correct term is HPA axis dysregulation. Offers of hydrocortisone or “adrenal support” from non-medical sources should be viewed critically.
DHEA and the Cortisol-DHEA Ratio
DHEA (dehydroepiandrosterone) is the second major adrenal hormone. It acts as cortisol’s counterplayer. Both come from the same precursor — pregnenolone. Under chronic stress the production shifts toward cortisol. DHEA drops. The cortisol/DHEA ratio rises.
DHEA-S (sulfate) reference values:
- Men 20–40 years: 200–560 µg/dl
- Women 20–40 years: 140–380 µg/dl
- Past 50: natural decline of 10–20 percent per decade
Cortisol/DHEA-S ratio as a marker for HPA dysregulation:
- Ratio below 5: balanced
- Ratio 5 to 10: elevated stress
- Ratio above 10: chronic distress
The ratio is more informative than individual values. It reflects adrenal axis balance. Whether treatment is appropriate with low DHEA is for the physician alone to decide, because DHEA converts to testosterone and estrogen in the body. Self-administration is not the subject of this article.
Cortisol and Other Biomarkers
Cortisol acts systemically. Its effects show up in multiple lab values.
Blood sugar and HbA1c. Cortisol mobilizes glucose from the liver. Chronically elevated cortisol is associated with insulin resistance. HbA1c above 5.7 percent despite a healthy diet can be a clue. Fasting blood glucose above 100 mg/dl combined with elevated cortisol strengthens the suspicion.
Inflammation (CRP). Acute cortisol dampens inflammation. Chronic elevated cortisol can cause glucocorticoid resistance in immune cells. Possible result: low-grade inflammation with hs-CRP above 1 mg/l. More in the guide on inflammation markers in blood.
Thyroid (TSH and fT3). Chronic stress inhibits the conversion of T4 to active T3. TSH may rise slightly, fT3 drops. This looks like subclinical hypothyroidism but can be secondary, driven by cortisol. Details in the guide on thyroid values.
Testosterone. Cortisol and testosterone compete. Chronically high cortisol is associated with lower free testosterone. The cortisol/testosterone ratio is regarded as a marker for overtraining and burnout.
Magnesium. Stress depletes magnesium. Low magnesium can amplify the stress response — a vicious cycle. Serum magnesium below 0.8 mmol/l with elevated cortisol is a typical pattern.
Factors Influencing the Cortisol Rhythm: What Research Examines
The following factors are examined in studies. The quality of evidence varies, and not every factor works equally for everyone. The sections describe the state of research; they are not instructions.
Sleep
Sleep is regarded as one of the strongest influences on cortisol. 7 to 9 hours per night are cited as the basis. Sleep research discusses, among other things:
- Morning daylight. Current understanding is that it stabilizes the circadian rhythm.
- Consistent sleep times. Irregularity is associated with elevated cortisol.
- Little light late in the evening. Blue light is considered disruptive to sleep.
- Cool room temperature. It is linked to the nocturnal cortisol low.
Breathing Techniques
Breathing is a direct route to the autonomic nervous system. Techniques described include box breathing (equal phases of inhaling, holding, exhaling, holding), 4-7-8 breathing with a prolonged exhale and the physiological sigh (double nasal inhale, long exhale). They are associated with activation of the parasympathetic nervous system; robust data on cortisol values are limited.
Meditation
Goyal et al. 2014 (JAMA Internal Medicine) analyzed 47 randomized trials in a meta-analysis. For 8-week MBSR programs (Mindfulness-Based Stress Reduction), cortisol values about 20 percent lower on average were reported. The studies differ in duration, measurement method and participants.
Exercise: Moderation and Overtraining
Exercise is double-edged. Moderate training is associated with lower cortisol, excessive training with chronically elevated cortisol.
- Moderate load: Endurance training at moderate heart rate is associated with favorable cortisol regulation.
- Strength training: Regular strength training is associated with a more favorable cortisol/testosterone ratio.
- Overtraining: Very long high-intensity sessions without enough recovery are considered a risk factor for overtraining syndrome with a conspicuous cortisol/testosterone ratio.
- Time of day: Very late intense training can disrupt the evening fall in cortisol.
Plant Extracts and Nutrients: State of the Evidence
Several plant extracts and nutrients are being researched in connection with cortisol. None of them is approved or proven as a remedy for elevated cortisol. Whether taking any of them is appropriate, and at what dose and for how long, belongs with a physician; interactions with medication and pre-existing conditions have to be considered.
Ashwagandha (Withania somnifera). In individual randomized, placebo-controlled studies (Chandrasekhar et al. 2012; Lopresti et al. 2019), morning cortisol in the ashwagandha group was lower than under placebo at the end of the study. Sleep, perceived stress and, in men, testosterone were also recorded. The evidence is limited and the extracts used differ. Occasional gastrointestinal complaints and, very rarely, thyroid activation are described as side effects.
Rhodiola rosea. The evidence is weaker. It is examined in connection with stress-related fatigue; its effect is not established.
Phosphatidylserine. Studies (Monteleone 1992, Starks 2008) examined the cortisol response to physical exertion. The results come from small, older studies and are not to be understood as a recommendation.
Vitamin C. Studies with ultra-runners (Peters et al. 2001) looked at the cortisol response after extreme exertion. For normal training there are no established findings that would justify taking it.
Magnesium. Magnesium is examined in connection with sleep and the stress response. The forms differ in tolerability and bioavailability. Details and form comparison in the guide on magnesium forms.
Omega-3 fatty acids. They are examined in connection with systemic inflammation, which in turn can be linked to chronically elevated cortisol. Rather moderate effects are reported; medical clarification makes sense here too, for example with blood-thinning medication.
Factors That Can Raise Cortisol
Some popular strategies are considered counterproductive.
Alcohol as “relaxation”. Subjectively calming, but associated with elevated cortisol in studies. A rise is described after about 2 standard drinks and can last until morning.
Caffeine on an empty stomach. Coffee during the first 60 minutes after waking can add to the CAR. An “afternoon crash” is described.
Extreme calorie restriction. Sustained, marked calorie deficits are associated with elevated cortisol. Intermittent fasting is described as compatible if total calories are adequate.
Caffeine-rich pre-workout products. Together with other stimulants they can raise acute cortisol sharply. This is described as unfavorable for trainees with chronic stress.
Overtraining Syndrome: Cortisol:Testosterone Ratio
If you train hard regularly, you can keep the cortisol/testosterone ratio in view. It is regarded as a sensitive marker for overtraining.
Calculation: Cortisol (nmol/l) ÷ Testosterone (nmol/l) × 100
- Ratio below 0.3: good recovery
- Ratio 0.3 to 0.5: borderline
- Ratio above 0.5: points to overtraining risk
- Ratio drop of more than 30 percent from baseline: sports medicine reads this as a sign of insufficient recovery
Follow-up measurements are common under intense training, especially during competition phases. In Lab2go you keep both values in your history and note sleep data and training volume next to them. Interpretation belongs with sports medicine.
Tracking: How Often and What
The sensible testing frequency depends on the situation and is set by a physician.
Baseline. One morning serum cortisol and DHEA-S form a starting point. Cost: 25–50 euros. Complements the basic panel from the understanding blood values guide.
With symptoms (sleep issues, burnout suspected). A 4-point saliva profile plus DHEA-S gives a full picture of the HPA axis. Cost: 60–100 euros.
With changes (e.g. sleep, training or medically supervised measures). Measurements before and after the change show how values develop.
Athletes. The cortisol/testosterone ratio is often followed at intervals of a few months, more closely during competition phases.
Document context. Sleep hours last week, training volume, subjective stress level (1–10), menstrual cycle phase for women. The raw value alone is only half the information.
For systematic tracking and trend analysis, check the features of Lab2go or compare plans and pricing.
Bottom Line: Cortisol Is Measurable and Can Be Put in Context
Cortisol is not an enemy. It is a rhythm that needs to be in balance. High in the morning, low in the evening. CAR intact, DHEA ratio stable. When the rhythm derails, clinicians speak of HPA dysregulation — not “adrenal fatigue”.
Three steps toward interpretation:
- Record a baseline. Morning serum cortisol between 7 and 9 am plus DHEA-S, ordered by a physician. Cost: 25–50 euros.
- Record context. Note sleep, training and stress level next to the values.
- Discuss results with a physician. Whether any measures make sense is for the physician to decide.
General background on dietary supplements is in the supplement beginners guide. Whether a supplement is appropriate for you at all is a medical question.
This article is for information only and does not replace medical advice. Taking anything, its dose and any therapy need to be clarified with a physician; no use is recommended. If your morning cortisol is below 3 µg/dl, above 30 µg/dl or you suspect Cushing or Addison disease, contact an endocrinologist. Self-tracking complements medicine. It does not replace it.
Article FAQ
- When is cortisol highest during the day?
- Cortisol peaks about 30 minutes after waking. This rise is called the Cortisol Awakening Response (CAR) and is 50 to 75 percent above the wake value. Cortisol then falls steadily until midday, reaches its low point late at night and starts rising again during the second half of the night. That is why timing is critical — a blood draw at 2 pm shows entirely different values than at 8 am.
- What are normal cortisol levels?
- Between 7 and 9 am, the serum reference range is 5 to 25 µg/dl (138 to 690 nmol/l). By afternoon it drops to 3 to 16 µg/dl, by midnight below 5 µg/dl. In saliva, morning values sit at 8 to 23 nmol/l and evening values below 2 nmol/l. Reference ranges differ by laboratory and method. Values outside these ranges can point to HPA axis dysregulation, Cushing syndrome or adrenal insufficiency; interpreting them is a medical task.
- What is adrenal fatigue?
- Adrenal fatigue is not a recognized medical condition. The Endocrine Society and all major endocrinology societies reject the diagnosis because no reproducible measurements or pathophysiological basis exist. What is discussed in the medical literature is HPA axis dysregulation — a decoupling between hypothalamus, pituitary and adrenal under chronic stress. It can be examined via cortisol and DHEA day profiles.
- What is known about ashwagandha, and when should it be medically checked?
- Ashwagandha has been examined in a few randomized, placebo-controlled studies, including Chandrasekhar et al. 2012 and Lopresti et al. 2019. In these, cortisol in the ashwagandha group was lower than under placebo at the end of the study; sleep quality and perceived stress were also recorded. The evidence is limited: there are few studies using different extracts. Occasional gastrointestinal complaints and, very rarely, thyroid activation are described as possible side effects. Whether taking it is appropriate, and at what dose and for how long, needs to be clarified with a physician, especially with thyroid conditions, pregnancy or medication. This article is not a recommendation to use it.
- Does alcohol raise cortisol?
- Studies report that alcohol can raise cortisol, even though it feels relaxing in the short term. A rise has been described after about 2 standard drinks, peaking 1 to 3 hours after drinking. The effect can last until the next morning and disturb the Cortisol Awakening Response. Chronic alcohol intake is associated with persistently elevated cortisol and disturbed sleep.
- How do caffeine and coffee affect cortisol?
- Caffeine can raise cortisol acutely, especially at high intake and on an empty stomach. About 3 to 4 cups of coffee a day are usually considered safe. Caffeine late in the afternoon can also disrupt sleep and favor evening cortisol spikes. It is also discussed that coffee directly after waking adds to the natural CAR. Individual tolerance and pre-existing conditions should be discussed with a physician.
- What does the evidence say about meditation and cortisol?
- The meta-analysis by Goyal et al. 2014 in JAMA Internal Medicine examined 8-week MBSR programs (Mindfulness-Based Stress Reduction) and reported cortisol values about 20 percent lower on average. The evidence is generally firmer than for many supplements, but studies differ in duration, measurement method and participants. Regularity of practice is the main factor discussed.
- Which cortisol testing method is best?
- For most questions the 4-point saliva day profile is regarded as informative. Measurements are taken at waking, 30 minutes later, midday and evening. This reveals the circadian rhythm and CAR. Morning serum cortisol only shows a single moment and can be distorted by blood draw stress. Hair cortisol measures the average load of the last 3 months. 24-hour urine is used less often today. Which method fits is decided by the treating physician.
- Can cortisol be too low?
- Yes, chronically low cortisol below 3 µg/dl in the morning may indicate primary (Addison disease) or secondary adrenal insufficiency. Symptoms include extreme fatigue, salt cravings, blood pressure drop on standing, skin pigmentation and weight loss. An Addisonian crisis is life-threatening. If suspected, an ACTH stimulation test is part of the medical workup. Self-diagnosing as 'adrenal fatigue' can delay the correct diagnosis.
- What does a cortisol test cost?
- Morning serum cortisol costs 15 to 25 euros as an out-of-pocket test. A 4-point saliva day profile runs 40 to 80 euros via online labs. Hair cortisol costs 60 to 120 euros and is only offered by specialized labs. With a medical indication, statutory insurance covers the cost. Which test makes sense is best discussed with a physician.
This article is for general information only and is not a substitute for individual medical advice, diagnosis, or treatment. Discuss any changes to your diet, supplementation, or medication with a qualified healthcare professional.
Maritta Schmid, Heilpraktikerin (licence under the German Heilpraktikergesetz; non-medical health practitioner), Licence under the German Heilpraktikergesetz, issued by Gesundheitsamt Heilbronn (February 2010), Supervisory authority: Landratsamt Ostalbkreis – Gesundheitsamt Aalen
Heilpraktikerin & Founder
Schwäbisch Gmünd, Germany
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