High cortisol in the morning: why it peaks and when it matters

High cortisol in the morning is normal. Cortisol is designed to be highest in the early part of the day and lowest around midnight, so a morning value that looks high next to an evening one is the pattern working as it should.

The real question is whether a morning level is high for the morning. This page explains the normal peak, the early-hours rise that people call a 3 a.m. spike, and the few situations where a morning value matters to a doctor.

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Why cortisol is highest in the morning

MedlinePlus says cortisol levels are normally highest in the morning and much lower around 4 p.m. The detail of the curve comes from review papers.

• A laboratory review in Diagnostics says that in people who are awake in the day, cortisol starts to rise from about 3 a.m. It is lowest shortly after falling asleep, at about midnight.
• A review in Endocrine Reviews says the rise starts from about 4 a.m. and peaks within 3 hours of waking. That is called the cortisol awakening response.
• A 2025 review in the International Journal of Molecular Sciences describes the peak as coming within 30 to 45 minutes after waking.

These timings differ a little between reviews. They agree on the shape: a climb over the last part of sleep, a peak shortly after waking, and a steady fall through the day. The same 2025 review says some studies show a small second rise in the early to mid afternoon, and that short pulses ride on top of the curve.

The pituitary hormone that drives cortisol, ACTH, follows the same curve. A 2022 paper in Academic Pathology puts the ACTH peak between 6 and 8 a.m. and the lowest point around 11 p.m. For the rhythm itself, see your body clock and cortisol and the cortisol awakening response.

What a normal morning level looks like

One published range for blood cortisol shows the usual fall from morning to afternoon.

Source	Morning	Afternoon
Review in Int J Mol Sci, 2025 (total serum cortisol)	3 to 23 µg/dL at 8 a.m.	3 to 13 µg/dL at 4 p.m.

Labs use different methods, and Endocrine Reviews says each clinical lab sets its own performance characteristics. Use the range printed on your report. Normal cortisol levels has more, and the cortisol units converter helps if your report uses nmol/L.

A value above your lab’s morning range is something to go over with a clinician. It is not a diagnosis, and it doesn’t tell you the cause.

Symptoms of high cortisol in the morning

No symptom marks a high morning cortisol. The sources we checked don’t tie any waking feeling, such as anxiety, early waking or a racing heart, to a cortisol level. What they show is that sleep and cortisol are linked in several directions:

• In the Whitehall II study of more than 3,000 adults, those who reported chronic insomnia symptoms had a steeper morning rise in cortisol than people with no sleep problems. This is an association, and it doesn’t show insomnia comes from cortisol.
• In a study of 23 young adults, one night of sleep deprivation was followed by lower morning cortisol.
• Endocrine Reviews says increasing age brings an earlier morning rise, and that some, but not all, chronic shift workers show a delayed rise.

If you want to know your cortisol, the only way is to measure it. See cortisol and sleep.

Cortisol spike at 3 a.m. and at night

People often ask about a cortisol spike at 3 a.m. What the sources describe is a normal rise starting around then, as above. They also describe two other things.

• In the second half of the night, when REM sleep dominates, Endocrine Reviews says the brakes on the stress-hormone system ease and its activity increases.
• Nocturnal awakenings at the end of sleep are associated with a short release of cortisol, followed by a short pause.

So waking at 3 a.m. doesn’t show a cortisol problem, and the feeling can’t be read as a cortisol level.

At night the opposite question is what doctors ask: does cortisol fall low enough? The late-night saliva test looks for a loss of that drop, which is why NIDDK says that in Cushing’s, “cortisol levels don’t drop”. Even that test can be thrown off by depression, shift work and disturbed sleep. See cortisol spikes.

When a morning level matters to doctors

• After a dexamethasone dose. In the low-dose dexamethasone suppression test, NIDDK says you take dexamethasone around 11 p.m. and have blood drawn at about 8 a.m. Cortisol that doesn’t drop suggests Cushing’s. In this test, the morning draw is read against the dose.
• A morning and later pair. MedlinePlus says blood samples are usually taken twice in a day, once in the morning and again around 4 p.m., and that this takes two appointments. The pair shows whether cortisol falls the way it should.
• Suspected low cortisol. A low morning value is what draws attention in adrenal insufficiency, a separate question covered under low cortisol.

A primary care review says using a random cortisol to screen for Cushing’s is unreliable and not recommended. Screening uses the timed and suppression tests above. A single blood cortisol can’t diagnose or rule out Cushing’s syndrome.

If you are thinking about a test

A morning and later pair is a reasonable way to get numbers to bring to a clinician, if you aren’t acutely unwell. Severe weakness, repeated vomiting, confusion or fainting need urgent care, not a test. It shows the fall across the day. It doesn’t screen for Cushing’s.

• Stress and exercise can raise cortisol, and MedlinePlus says you may need to rest before the test.
• The seller’s page for its morning-and-later test gives typical draw windows of 7 to 9 a.m. and 3 to 5 p.m. It also describes the second sample as taken in the afternoon in one place and at night in another, and doesn’t say whether it is one visit or two. Check this before you order, and follow the timing on your lab order.
• The seller’s page states no fasting rule, so follow the instructions on your order.
• If you take a steroid medicine, tell your prescriber first. Don’t stop or change it for a test.

Our page on AM and PM timing covers the practical side.

Questions people ask

Why is cortisol highest in the morning?

It follows a daily rhythm that prepares the body for the day. MedlinePlus says cortisol is normally highest in the morning. The rise starts during the last part of sleep, as above.

Is a high morning cortisol bad?

Not by itself. A high-looking morning value is the normal peak. A result above your lab’s morning range is a reason to talk to a clinician, who will look at timing, medicines, stress on the day and other tests.

What is the cortisol awakening response?

It is the extra rise in cortisol soon after waking. One review above places its peak within 30 to 45 minutes of waking and another within 3 hours. In research it is often measured with saliva samples, as in the Whitehall II study. See the cortisol awakening response.

Keep reading

• High cortisol symptoms

  The signs doctors link to too much cortisol.

• Cortisol spikes

  What a spike is and what it isn't.

• AM and PM cortisol timing

  When the samples are taken and why timing matters.

• Normal cortisol levels

  Published ranges by time of day, with sources.

• The cortisol awakening response

  The rise after waking.