Morris, Gerwyn, Anderson, George, Galecki, Piotr et al. · BMC medicine · 2013 · DOI
This study compares ME/CFS with sickness behavior—the tired, achy feeling you get when you have the flu. While ME/CFS and sickness behavior share some symptoms like fatigue and body pain, they are fundamentally different conditions. Sickness behavior is your body's helpful, temporary response to infection that goes away once you recover, whereas ME/CFS is a chronic disease that persists long-term and involves ongoing immune system problems.
This research helps clarify that ME/CFS is not simply a prolonged version of normal sickness, which is important for establishing it as a distinct medical condition deserving dedicated research and treatment approaches. Understanding these differences strengthens the scientific foundation for recognizing ME/CFS as a serious, disabling disease requiring its own therapeutic strategies rather than standard infection recovery protocols.
This review does not establish the specific mechanisms causing ME/CFS or prove causative relationships between immune activation and symptoms. It also does not identify which infection or inflammatory triggers lead to ME/CFS development, nor does it provide evidence that sickness behavior could never progress into ME/CFS in certain individuals.
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
Morris, Gerwyn, Anderson, George, Galecki, Piotr, Berk, Michael, & Maes, Michael (2013). A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and sickness behavior.. BMC medicine. https://doi.org/10.1186/1741-7015-11-64
BibTeX
@article{mecfsatlas-morris-2013-narrative-review,
author = {Morris, Gerwyn and Anderson, George and Galecki, Piotr and Berk, Michael and Maes, Michael},
title = {A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and sickness behavior.},
journal = {BMC medicine},
year = {2013},
doi = {10.1186/1741-7015-11-64},
note = {PubMed: 23497361},
url = {https://www.mecfsatlas.com/evidence/morris-2013-narrative-review},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/morris-2013-narrative-review
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