Quick answer: Cortisol is the main stress hormone made by the adrenal glands. It follows a daily rhythm: highest in the morning and lowest at night. It helps regulate blood sugar, blood pressure, immunity and energy. Very high cortisol (Cushing’s) or very low cortisol (adrenal insufficiency) are medical conditions; more subtle rhythm changes can come with chronic stress and poor sleep.
What is Cortisol?
Cortisol is a steroid hormone released by the adrenal glands in response to signals from the brain. It follows a daily rhythm and rises with stress. This marker is part of the Healthspan Assessment panel available to my 1-on-1 patients.
Why Cortisol matters
- Blood sugar regulation
- Blood pressure
- Immune and inflammation control
- Energy and alertness
- Sleep-wake rhythm
Understanding your result
Reference ranges vary by lab, age and sex. Your provider interprets your result against the lab’s range and your overall picture, rather than chasing a single number. Functional labs are optional. They can be helpful in more complex cases, and in my practice they are available only to patients working 1-on-1 with me.
What low Cortisol can mean
- Adrenal insufficiency (Addison’s disease)
- Pituitary problems
- Stopping steroid medications abruptly
What high Cortisol can mean
- Chronic stress and poor sleep
- Cushing’s syndrome
- Steroid medications
- Severe illness
What affects Cortisol
- Time of day
- Stress, sleep and caffeine
- Medications, including steroids and birth control
- Test type (blood, saliva or urine)
Ways to support healthy levels
- Morning light and a consistent sleep schedule
- Regular meals with protein
- Stress practices such as breathwork (see breathwork)
- Adaptogens with guidance (see adaptogens)
Cortisol and healthy aging
Chronically high cortisol raises blood sugar, suppresses repair, fuels inflammation and is associated with shorter telomeres. A healthy daily rhythm supports healthy aging. For rhythm patterns, see cortisol patterns.
When to see a naturopathic doctor
- Fatigue, poor sleep or feeling wired at night
- Weight gain around the middle with high blood pressure
- Chronic stress affecting your health
- You want cortisol results explained
See a medical provider promptly for severe weakness, dizziness, vomiting, low blood pressure or salt cravings (possible adrenal crisis), or rapid weight gain with purple stretch marks.
Want help making sense of your labs?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Frequently asked questions
When should cortisol be tested?
Blood cortisol is usually tested in the morning. Saliva or urine tests can show the daily pattern.
What does high cortisol mean?
It can reflect stress, medications or, rarely, Cushing’s syndrome.
What does low cortisol mean?
It can signal adrenal insufficiency, which needs medical evaluation.
Is adrenal fatigue real?
It is not a recognized diagnosis, but stress-related changes in cortisol rhythm are real.
Sources
- Adam EK, et al. Diurnal cortisol slopes and mental and physical health outcomes: a systematic review and meta-analysis. Psychoneuroendocrinology 2017. PMID: 28578301. https://pmc.ncbi.nlm.nih.gov/articles/PMC5568897/
- Cain DW, Cidlowski JA. Immune regulation by glucocorticoids. Nat Rev Immunol 2017. PMID: 28192415. https://pmc.ncbi.nlm.nih.gov/articles/PMC9761406/
- Tomiyama AJ, et al. Does cellular aging relate to patterns of allostasis? An examination of basal and stress reactive HPA axis activity and telomere length. Physiol Behav 2012. PMID: 22138440. https://pmc.ncbi.nlm.nih.gov/articles/PMC3361080/
- MedlinePlus: Cortisol Test
- MedlinePlus: Adrenal Gland Disorders
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
Free: The 28-Day Longevity Reset
A simple day-by-day email guide to sleep, movement, food, and daily habits that support healthy aging. It’s free, and you can unsubscribe anytime.
Get the free guide
