Jason, Leonard A, Evans, Meredyth, Brown, Molly et al. · PM & R : the journal of injury, function, and rehabilitation · 2010 · DOI
This article explores what fatigue really is and how doctors can tell the difference between normal tiredness and the severe, disabling fatigue that comes with illnesses like ME/CFS. Fatigue is common in many diseases and conditions, but researchers have had difficulty measuring it consistently and understanding why it happens. The authors review the scientific literature to help clarify these important questions.
Understanding the distinction between normal fatigue and pathological fatigue is fundamental to ME/CFS research and clinical practice. This review helps establish a clearer framework for assessing fatigue in ME/CFS, which is essential for diagnosis, measuring treatment outcomes, and communicating the severity of the illness to healthcare providers and society.
As a review article, this study does not provide new experimental data or evidence about the causes of ME/CFS-related fatigue. It cannot establish whether fatigue in ME/CFS arises from specific biological mechanisms or how it compares mechanistically to fatigue in other diseases. The conclusions reflect the state of existing literature rather than novel findings.
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
Jason, Leonard A, Evans, Meredyth, Brown, Molly, & Porter, Nicole (2010). What is fatigue? Pathological and nonpathological fatigue.. PM & R : the journal of injury, function, and rehabilitation. https://doi.org/10.1016/j.pmrj.2010.03.028
BibTeX
@article{mecfsatlas-jason-2010-what-fatigue,
author = {Jason, Leonard A and Evans, Meredyth and Brown, Molly and Porter, Nicole},
title = {What is fatigue? Pathological and nonpathological fatigue.},
journal = {PM & R : the journal of injury, function, and rehabilitation},
year = {2010},
doi = {10.1016/j.pmrj.2010.03.028},
note = {PubMed: 20656613},
url = {https://www.mecfsatlas.com/evidence/jason-2010-what-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/jason-2010-what-fatigue
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