Cortisol and the glucocorticoids

On this page

1. What is cortisol?
2. Where is cortisol produced?
3. Function of cortisol
4. The three phases of the stress response
5. Cortisol and fertility
6. Normal cortisol levels
7. Causes of high cortisol
8. Causes of low cortisol
9. When and how to test cortisol
10. Cortisol in traditional Chinese medicine
11. Acupuncture and cortisol
12. Chinese herbal medicine and cortisol
13. Diet and lifestyle
14. Related pages

1. What is cortisol?

Cortisol is the body's primary stress hormone and the most important of the glucocorticoids — a group that also includes corticosterone and cortisone. Cortisol is produced by the adrenal glands in response to stress (physical, psychological or metabolic) and follows a strong daily rhythm — high in the morning to wake us up, gradually falling through the day, and lowest around midnight.

While short bursts of cortisol are essential for survival and good health, chronically elevated cortisol — the kind produced by ongoing stress — has profound effects on fertility and almost every other body system.

Reference ranges vary from country to country and between laboratories. Always interpret your own result against the reference range provided by the laboratory that performed your test.

2. Where is cortisol produced?

Cortisol is produced by the cortex of the adrenal glands, which sit on top of each kidney. Its production is regulated by a feedback loop:

1. The hypothalamus releases corticotrophin-releasing hormone (CRH).
2. CRH stimulates the pituitary to release adrenocorticotrophic hormone (ACTH).
3. ACTH stimulates the adrenal cortex to produce cortisol.
4. Cortisol then negatively feeds back on both the hypothalamus and pituitary to switch the system off — unless ongoing stress overrides this.

3. Function of cortisol

Cortisol has many functions:

1. Mobilising glucose and fatty acids for energy in response to stress.
2. Suppressing inflammation and immune function — useful in acute injury, harmful when chronic.
3. Regulating blood pressure.
4. Maintaining the daily wake-sleep rhythm.
5. Modulating mood, alertness and cognitive function.

4. The three phases of the stress response

The body's response to stress occurs in three phases:

1. Alarm phase (level 1) — short-lived "fight or flight" response with adrenaline and a brief cortisol rise.
2. Resistance phase (level 2) — sustained, chronic elevation of cortisol when stress lasts more than a few hours. Most people in modern life live in this phase. Energy, lipid and protein reserves are depleted, fertility hormones become irregular, and leptin signalling is impaired.
3. Exhaustion phase (level 3) — when chronic stress finally exhausts the adrenals, cortisol may fall (so-called "adrenal fatigue") and the person experiences profound exhaustion, low mood and immune dysfunction.

5. Cortisol and fertility

Chronically elevated cortisol affects fertility in several ways:

1. Suppresses GnRH, leading to irregular cycles and anovulation.
2. Diverts pregnenolone (the precursor of both cortisol and progesterone) towards cortisol production — the "pregnenolone steal" — leading to low progesterone.
3. Reduces TH2 immune cells needed for embryo implantation.
4. Reduces ovarian and uterine blood flow.
5. Worsens insulin resistance, exacerbating PCOS.
6. Reduces oxytocin, the bonding hormone.

Research has shown that women starting fertility treatment with elevated cortisol have lower success rates. Reducing cortisol is therefore one of the most important fertility-supportive interventions.

6. Normal cortisol levels

Typical reference ranges for serum cortisol are approximately:

1. Morning (8–9 a.m.): 140–700 nmol/L (5–25 µg/dL).
2. Evening (4–5 p.m.): 80–300 nmol/L.
3. Late evening (11 p.m.): <100 nmol/L.

Reference ranges vary from country to country and between laboratories.

7. Causes of high cortisol

High cortisol is caused by:

1. Chronic psychological stress — the most common cause.
2. Sleep deprivation and shift work.
3. Excessive endurance exercise.
4. Chronic dieting and undereating.
5. Chronic illness or pain.
6. High caffeine and alcohol intake.
7. Cushing's syndrome (rare).
8. Synthetic glucocorticoid medications — prednisolone, dexamethasone etc.

8. Causes of low cortisol

Low cortisol is less common and is seen in:

1. Adrenal insufficiency (Addison's disease) — primary adrenal failure.
2. Pituitary insufficiency — secondary adrenal failure.
3. Long-term suppression by exogenous steroids.
4. Chronic exhaustion phase of the stress response.

9. When and how to test cortisol

Serum cortisol is usually measured in the morning (between 8–9 a.m.) when levels are at their peak. Salivary cortisol provides a more accessible way to measure cortisol multiple times across the day, capturing the daily rhythm. 24-hour urine cortisol gives a measure of total daily cortisol production. Hair cortisol, used in research, gives a measure of cortisol over the past 1–3 months.

Reference ranges vary from country to country. Always interpret your own result against the laboratory's reference range and discuss it with your doctor.

10. Cortisol in traditional Chinese medicine

In traditional Chinese medicine, the chronic elevation of cortisol from ongoing stress most closely matches the pattern of Liver Qi stagnation transforming into Heat, with consumption of Kidney Yin and eventually Kidney Yang. The exhaustion phase corresponds to severe Kidney Yang and Qi deficiency. Symptoms typically include irritability, tension headaches, irregular cycles, breast tenderness, sleep disturbance and eventually exhaustion.

11. Acupuncture and cortisol

Research has shown that acupuncture is highly effective at reducing cortisol levels by acting on the hypothalamic-pituitary-adrenal (HPA) axis. The deeply relaxing experience of acupuncture, the regulation of the autonomic nervous system, and the release of endorphins and oxytocin all contribute. Reducing cortisol with acupuncture is one of the major mechanisms by which it improves fertility outcomes — particularly in IVF.

12. Chinese herbal medicine and cortisol

Chinese herbal medicine has a rich tradition of formulae for stress-related disorders. The most commonly used is Xiao Yao San (Free and Easy Wanderer) and its modifications Jia Wei Xiao Yao San and Dan Zhi Xiao Yao San. Where stress has progressed to Kidney deficiency, formulae such as Liu Wei Di Huang Wan or You Gui Wan are added. Adaptogenic herbs including ginseng, rhodiola and ashwagandha (more commonly used in Ayurveda) can also be helpful.

13. Diet and lifestyle

To reduce chronically elevated cortisol:

1. Reduce psychological stress through mindfulness, meditation, yoga, t'ai chi, qi gong or counselling.
2. Sleep before 10 p.m. and aim for seven to eight hours per night.
3. Avoid excessive endurance exercise — three sessions of moderate cardio per week is sufficient.
4. Reduce caffeine — particularly after midday.
5. Limit alcohol.
6. Have fun! Watch comedies, spend time with friends, do things you enjoy.
7. Have regular acupuncture, massage or other relaxation-based therapies.
8. Avoid prolonged dieting and undereating, both of which raise cortisol.

14. Related pages

• Fertility hormones directory
• Dehydroepiandrosterone (DHEA)
• Oxytocin
• Progesterone
• Prolactin
• Unexplained infertility
• Repeated IVF failure
• My Fertility Guide