Togo, Fumiharu, Natelson, Benjamin H · Autonomic neuroscience : basic & clinical · 2013 · DOI
This study looked at how the heart's rhythm changes during sleep in ME/CFS patients compared to healthy people, and whether these changes relate to feeling more or less tired after sleep. Researchers found that some ME/CFS patients who woke up feeling sleepier had different heart rhythm patterns during deep sleep than healthy controls, even though standard sleep measurements looked normal. This suggests the nervous system's control of the heart during sleep might be disrupted in ME/CFS, which could contribute to unrefreshing sleep.
Many ME/CFS patients report profound unrefreshing sleep despite apparently normal sleep architecture on standard tests. This study identifies a subtle physiological marker (heart rate variability patterns) that standard sleep studies miss, potentially explaining why patients wake unrefreshed and providing a new avenue for understanding sleep dysfunction in ME/CFS.
This study does not prove that abnormal heart rate variability causes unrefreshing sleep—it only shows a correlation. It cannot establish whether the heart rhythm changes are a primary feature of ME/CFS or a secondary consequence of the illness. The small sample size and lab setting (first-night effects) limit generalizability to typical home sleep patterns.
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
Togo, Fumiharu & Natelson, Benjamin H (2013). Heart rate variability during sleep and subsequent sleepiness in patients with chronic fatigue syndrome.. Autonomic neuroscience : basic & clinical. https://doi.org/10.1016/j.autneu.2013.02.015
BibTeX
@article{mecfsatlas-togo-2013-heart-rate,
author = {Togo, Fumiharu and Natelson, Benjamin H},
title = {Heart rate variability during sleep and subsequent sleepiness in patients with chronic fatigue syndrome.},
journal = {Autonomic neuroscience : basic & clinical},
year = {2013},
doi = {10.1016/j.autneu.2013.02.015},
note = {PubMed: 23499514},
url = {https://www.mecfsatlas.com/evidence/togo-2013-heart-rate},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/togo-2013-heart-rate
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