What you've heard
Chronic stress wears out your adrenal glands, a condition called adrenal fatigue, and saliva tests and adrenal supplements can fix it
Verdict
False
False. If you are exhausted, see a clinician rather than the supplement aisle.
Is adrenal fatigue real?
False. If you are exhausted, see a clinician rather than the supplement aisle.
A systematic review found "no substantiation that 'adrenal fatigue' is an actual medical condition," and concluded that it "is still a myth." The Endocrine Society says no test can detect it, and warns that adrenal hormone supplements taken without need can stop your own glands making the hormones you need under physical stress, risking a life-threatening crisis when the pills stop. What is real: a flattened daily cortisol rhythm, weakly linked to poorer health, and true adrenal failure (Addison's disease), a separate illness that doctors can test for.12
Where the book tests it
What the book recommends instead
Practice slow breathing or mindfulness for five to ten minutes a day, or take an eight-week course
ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.How: breathe about six times a minute, roughly four seconds in and six out, sitting down, on most days; use a count, an app or a prayer to keep the pace. For anxiety that persists, consider an eight-week mindfulness-based stress reduction course. Why: small-to-moderate reductions in stress and anxiety in trials, and one course proved no worse than a standard drug for anxiety disorders.
Sources
- 12.Cadegiani, F.A., and Kater, C.E. (2016). "Adrenal fatigue does not exist: a systematic review." BMC Endocrine Disorders, 16(1), 48. https://doi.org/10.1186/s12902-016-0128-4 (58 studies.) ; Endocrine Society (2022). "Adrenal Fatigue." https://www.endocrine.org/patient-engagement/endocrine-library/adrenal-fatigue (Page last updated 25 January 2022; read September 2026.)
Note numbers are those of Chapter 13, Stress and the Mind.
This verdict is one of the "What you've heard" boxes in Chapter 13, Stress and the Mind, where the book tests the claims people repeat against the studies behind them.
Educational content, not medical advice. Disclaimer.