Doljansky, J T, Kannety, H, Dagan, Y · Chronobiology international · 2005 · DOI
A 47-year-old man with chronic fatigue syndrome developed a severely disrupted sleep-wake cycle after 20 years of working under very bright lights (used for diamond grading) often late into the night. When he switched to treatment combining melatonin at bedtime, bright light therapy in the morning, and avoiding bright light at night, his sleep pattern stabilized and his daytime tiredness improved significantly within one week.
Many ME/CFS patients experience disrupted sleep and circadian dysfunction, which often worsens fatigue and daytime symptoms. This case illustrates how occupational or environmental bright light exposure at the wrong time of day can severely disrupt circadian biology and suggests that modified light exposure—combined with melatonin—may be a recoverable contributing factor worth investigating in other CFS patients.
This single case report cannot establish that bright light exposure is a common cause of CFS or circadian dysfunction, nor can it prove causality versus coincidence. The lack of a control group, long-term follow-up, or assessment of whether the patient's CFS itself improved (versus only sleep pattern) limits generalizability. It does not clarify whether occupational light exposure is relevant to typical CFS populations.
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 →
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Primary citation
Doljansky, J T, Kannety, H, & Dagan, Y (2005). Working under daylight intensity lamp: an occupational risk for developing circadian rhythm sleep disorder?. Chronobiology international. https://doi.org/10.1081/CBI-200062422
BibTeX
@article{mecfsatlas-doljansky-2005-working-under,
author = {Doljansky, J T and Kannety, H and Dagan, Y},
title = {Working under daylight intensity lamp: an occupational risk for developing circadian rhythm sleep disorder?},
journal = {Chronobiology international},
year = {2005},
doi = {10.1081/CBI-200062422},
note = {PubMed: 16076658},
url = {https://www.mecfsatlas.com/evidence/doljansky-2005-working-under},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/doljansky-2005-working-under
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