Wood, B, Wessely, S, Papadopoulos, A et al. · Neuropsychobiology · 1998 · DOI
This study measured cortisol (a stress hormone) levels in the saliva of 10 people with ME/CFS and 10 healthy people over a 16-hour period. Contrary to some earlier research, people with ME/CFS actually had slightly higher cortisol levels on average than healthy controls. This finding suggests that low cortisol is not the cause of fatigue in ME/CFS.
This study challenges the hypothesis that low cortisol causes ME/CFS fatigue, redirecting research toward other biological mechanisms. Understanding cortisol's actual role in ME/CFS is important for developing targeted treatments and for validating or ruling out potential biomarkers.
This study does not prove that cortisol plays no role in ME/CFS pathology—elevated levels do not exclude cortisol dysregulation or abnormal cortisol signaling. The finding of higher mean cortisol does not explain the cause of fatigue or identify what dysregulation might be occurring. It also does not apply to CFS patients with concurrent depression, which was excluded.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Wood, B, Wessely, S, Papadopoulos, A, Poon, L, & Checkley, S (1998). Salivary cortisol profiles in chronic fatigue syndrome.. Neuropsychobiology. https://doi.org/10.1159/000026469
BibTeX
@article{mecfsatlas-wood-1998-salivary-cortisol,
author = {Wood, B and Wessely, S and Papadopoulos, A and Poon, L and Checkley, S},
title = {Salivary cortisol profiles in chronic fatigue syndrome.},
journal = {Neuropsychobiology},
year = {1998},
doi = {10.1159/000026469},
note = {PubMed: 9438265},
url = {https://www.mecfsatlas.com/evidence/wood-1998-salivary-cortisol},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/wood-1998-salivary-cortisol
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