García-Borreguero, D, Dale, J K, Rosenthal, N E et al. · Psychiatry research · 1998 · DOI
Many people experience changes in energy, mood, appetite, and sleep across different seasons, often feeling worse in winter. This study tested whether ME/CFS patients experience these same seasonal changes. The researchers found that ME/CFS patients actually show much less seasonal variation in their symptoms compared to healthy people, suggesting their fatigue and other symptoms stay relatively constant year-round rather than fluctuating with the seasons.
This finding is clinically significant because it suggests ME/CFS has a fundamentally different physiological basis than seasonal mood disorders, which may inform treatment approaches. Understanding that ME/CFS symptoms remain stable across seasons helps clinicians and patients recognize that symptom fluctuations may be driven by factors other than environmental seasonality, such as disease-specific mechanisms or activity patterns.
This study does not prove that seasonal factors never influence individual ME/CFS patients—there may be patient subgroups with seasonal sensitivity not detected in group-level analysis. It also does not establish why ME/CFS patients lack seasonal variation; the underlying biological mechanism remains unclear. The cross-sectional design cannot determine causation or whether this reduced seasonal sensitivity is a primary feature of ME/CFS or a secondary consequence of the illness.
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
García-Borreguero, D, Dale, J K, Rosenthal, N E, Chiara, A, O'Fallon, A, Bartko, J J, et al. (1998). Lack of seasonal variation of symptoms in patients with chronic fatigue syndrome.. Psychiatry research. https://doi.org/10.1016/s0165-1781(97)00141-8
BibTeX
@article{mecfsatlas-garca-borreguero-1998-lack-seasonal,
author = {García-Borreguero, D and Dale, J K and Rosenthal, N E and Chiara, A and O'Fallon, A and Bartko, J J and Straus, S E},
title = {Lack of seasonal variation of symptoms in patients with chronic fatigue syndrome.},
journal = {Psychiatry research},
year = {1998},
doi = {10.1016/s0165-1781(97)00141-8},
note = {PubMed: 9541142},
url = {https://www.mecfsatlas.com/evidence/garca-borreguero-1998-lack-seasonal},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/garca-borreguero-1998-lack-seasonal
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