Fischler, B, Le Bon, O, Hoffmann, G et al. · Neuropsychobiology · 1997 · DOI
This study examined sleep patterns in 49 ME/CFS patients compared to 20 healthy people using overnight sleep monitoring. Patients with ME/CFS had difficulty falling asleep and staying asleep, and spent less time in deep, restorative stage 4 sleep. These sleep problems were distinctive enough that researchers could correctly identify who had ME/CFS based on sleep patterns alone.
Sleep disturbances are a cardinal feature of ME/CFS, yet their objective characteristics were poorly understood in 1997. This study provides objective polysomnographic evidence that specific, measurable sleep abnormalities distinguish ME/CFS patients from healthy controls, supporting the biological basis of the illness and suggesting sleep dysfunction as a core pathological feature rather than merely a symptom of psychiatric comorbidity.
This study demonstrates correlation between ME/CFS and specific sleep abnormalities but does not establish causation—whether sleep dysfunction causes ME/CFS symptoms, results from them, or both arise from a common biological mechanism remains unclear. The cross-sectional design cannot determine if sleep disturbances precede or follow illness onset. The relatively small sample size and lack of longitudinal follow-up limit generalizability.
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
Fischler, B, Le Bon, O, Hoffmann, G, Cluydts, R, Kaufman, L, & De Meirleir, K (1997). Sleep anomalies in the chronic fatigue syndrome. A comorbidity study.. Neuropsychobiology. https://doi.org/10.1159/000119331
BibTeX
@article{mecfsatlas-fischler-1997-sleep-anomalies,
author = {Fischler, B and Le Bon, O and Hoffmann, G and Cluydts, R and Kaufman, L and De Meirleir, K},
title = {Sleep anomalies in the chronic fatigue syndrome. A comorbidity study.},
journal = {Neuropsychobiology},
year = {1997},
doi = {10.1159/000119331},
note = {PubMed: 9170115},
url = {https://www.mecfsatlas.com/evidence/fischler-1997-sleep-anomalies},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/fischler-1997-sleep-anomalies
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