Korszun, A, Sackett-Lundeen, L, Papadopoulos, E et al. · The Journal of rheumatology · 1999
This study looked at melatonin—a hormone that helps control sleep and daily rhythms—in women with fibromyalgia and chronic fatigue syndrome. Researchers collected blood samples every 10 minutes over 24 hours and found that women with fibromyalgia had higher melatonin levels at night compared to healthy controls, but women with chronic fatigue syndrome did not. The authors concluded there is no evidence that taking melatonin supplements would help these patients.
Sleep disturbance and circadian dysfunction are prominent features in ME/CFS, and melatonin supplementation is widely used by patients seeking relief. This study provides empirical evidence that melatonin levels are not uniformly low in these conditions, which challenges the rationale for replacement therapy and highlights the need for more nuanced understanding of circadian dysfunction in ME/CFS.
This study does not establish whether melatonin supplementation is clinically harmful or beneficial, nor does it explain the mechanisms of circadian dysfunction in ME/CFS. The small sample size and cross-sectional design limit generalizability, and the study does not measure symptom severity or clinical outcomes related to melatonin use. Additionally, elevated melatonin levels may reflect a compensatory response rather than a primary cause of disease.
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
Korszun, A, Sackett-Lundeen, L, Papadopoulos, E, Brucksch, C, Masterson, L, Engelberg, N C, et al. (1999). Melatonin levels in women with fibromyalgia and chronic fatigue syndrome.. The Journal of rheumatology. https://pubmed.ncbi.nlm.nih.gov/10606381/
BibTeX
@article{mecfsatlas-korszun-1999-melatonin-levels,
author = {Korszun, A and Sackett-Lundeen, L and Papadopoulos, E and Brucksch, C and Masterson, L and Engelberg, N C and Haus, E and Demitrack, M A and Crofford, L},
title = {Melatonin levels in women with fibromyalgia and chronic fatigue syndrome.},
journal = {The Journal of rheumatology},
year = {1999},
note = {PubMed: 10606381},
url = {https://www.mecfsatlas.com/evidence/korszun-1999-melatonin-levels},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/korszun-1999-melatonin-levels
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