Rahman, Khairunnessa, Burton, Alexander, Galbraith, Sally et al. · Sleep · 2011 · DOI
Researchers wanted to know if ME/CFS is caused by problems with the body's internal biological clock. They studied 15 people with ME/CFS and 15 healthy controls for 5 days, measuring sleep patterns, daily activity, stress hormone levels, and heart function. While people with ME/CFS reported worse fatigue, sleep problems, and pain, the researchers found no differences in actual sleep patterns or biological rhythms between the groups.
This study challenges the hypothesis that ME/CFS is fundamentally caused by circadian rhythm disturbances, redirecting research focus toward autonomic nervous system dysfunction. Understanding the activity-symptom relationship and the role of heart rate variability offers practical insights for activity management strategies in clinical treatment.
This study does not prove that circadian rhythms are completely normal in ME/CFS—it only found no group-level differences in the measures tested. It does not establish causation between afternoon activity and evening fatigue, only association. The small sample size (15 per group) means findings may not apply to all ME/CFS patients, and the 5-day observation period may be too brief to detect subtle or variable circadian abnormalities.
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
Rahman, Khairunnessa, Burton, Alexander, Galbraith, Sally, Lloyd, Andrew, & Vollmer-Conna, Ute (2011). Sleep-wake behavior in chronic fatigue syndrome.. Sleep. https://doi.org/10.1093/sleep/34.5.671
BibTeX
@article{mecfsatlas-rahman-2011-sleep-wake,
author = {Rahman, Khairunnessa and Burton, Alexander and Galbraith, Sally and Lloyd, Andrew and Vollmer-Conna, Ute},
title = {Sleep-wake behavior in chronic fatigue syndrome.},
journal = {Sleep},
year = {2011},
doi = {10.1093/sleep/34.5.671},
note = {PubMed: 21532961},
url = {https://www.mecfsatlas.com/evidence/rahman-2011-sleep-wake},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-27. https://www.mecfsatlas.com/evidence/rahman-2011-sleep-wake
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