History
In the 1930s Edward Kendall at the Mayo Clinic and Tadeus Reichstein in Switzerland isolated a series of steroids from the adrenal cortex; the one Kendall called "Compound E" is cortisone. In 1948 Philip Hench injected it into a woman crippled by rheumatoid arthritis, and within days she could walk, so it was hailed as a miracle drug; the three shared the 1950 Nobel Prize in Physiology or Medicine. Meanwhile, in 1936 Hans Selye described a "general adaptation syndrome," a common bodily response to many kinds of harm, founding the modern idea of stress.
Daily rhythm and role
When the brain senses a threat, the hypothalamus releases CRH, the pituitary releases ACTH, and the adrenal glands pour out cortisol. Cortisol makes the liver produce glucose, tamps down immune activity and inflammation, and sharpens focus for a crisis. Normal cortisol follows a circadian rhythm, peaking 30 to 45 minutes after waking and bottoming out around midnight. That's why blood tests are usually done in the morning, while late-night saliva cortisol is used to screen for overproduction.
Too much or too little
Chronically high cortisol from long-term stress is linked to belly fat, higher blood sugar, high blood pressure, poor sleep and memory problems. Extreme excess, often from a tumor, causes Cushing's syndrome, while adrenal failure causes Addison's disease, with fatigue, low blood pressure and darkened skin. "Adrenal fatigue," though popular online, isn't a recognized diagnosis. Stopping long-term steroid pills abruptly is dangerous because the adrenals can't restart right away, so doses must be tapered. Researchers are also studying how burnout alters the cortisol rhythm.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- How can I lower my cortisol?
- Regular sleep, moderate aerobic exercise, meditation or slow breathing, less caffeine and alcohol, and time with other people are all supported by evidence.
- Does morning coffee spike cortisol?
- Caffeine can nudge cortisol up a little, but regular drinkers adapt and the effect shrinks. It's not a major concern.
Sources reviewed: 2026-10-26
References
- Hench, P. S., Kendall, E. C., Slocumb, C. H., & Polley, H. F. (1949). The effect of a hormone of the adrenal cortex (17-hydroxy-11-dehydrocorticosterone: compound E) and of pituitary adrenocorticotropic hormone on rheumatoid arthritis. Proceedings of the Staff Meetings of the Mayo Clinic, 24, 181–197.
- Selye, H. (1936). A syndrome produced by diverse nocuous agents. Nature, 138, 32.
- Sapolsky, R. M., Romero, L. M., & Munck, A. U. (2000). How do glucocorticoids influence stress responses? Endocrine Reviews, 21(1), 55–89.