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Electroencephalographic (EEG) Correlates Of Chronic Fatigue Syndrome During Sleep

corelates_chronic_fatigue_article_coverChronic fatigue syndrome (CFS) presents clinically as incapacitating physical and mental fatigue, frequently accompanied by unrefreshing sleep, impaired memory and concentration, and diffuse musculoskeletal pain. An absence of characteristic clinical signs or diagnostic laboratory abnormalities further create a diagnostic challenge. Adding to this complexity, the clinical picture of CFS is similar to that observed with sleep disorders. Yet, no reproducible perturbations of sleep architecture, multiple sleep latency times, or Epworth Sleepiness Scores are found to be associated consistently with CFS. This led to the hypothesis that sleep homeostasis, rather than sleep architecture, may be perturbed in CFS. Check the end of this report for a link to download a PDF of this open access article.

Methods
35 CFS and 40 control subjects, all adult, were evaluated overnight polysomnography (PSG). PSG records were manually scored and epochs containing artifact removed. Fast Fourier Transformation was utilized to deconstruct individual electroencephalographic (EEG) signals into primary frequency bands of alpha, delta, theta, sigma, and beta frequency domains. The spectral power of each frequency domain for each sleep state was compared between persons with CFS and matched controls.

Results
In persons with CFS, delta power was diminished during slow wave sleep (SWS), but elevated during both stage 1 and rapid eye movement (REM) sleep. Alpha power was reduced during stage 2, slow wave, and REM sleep. Those with CFS also had significantly lower theta, sigma, and beta spectral power during stage 2, Slow Wave Sleep, and REM.

Discussion
A quantitative EEG analysis demonstrated reduced spectral power of cortical delta activity during SWS. The researchers also found reduced spectral power of cortical alpha activity, with the greatest reduction occurring during REM sleep. Reductions in theta, beta, and sigma spectral power were also apparent.

Conclusion
Unremitting fatigue and unrefreshing sleep, the waking manifestations of CFS, may be the consequence of impaired sleep homeostasis rather than a primary sleep disorder.

Material adapted by CFisher from:

Michael J. Decker, Humyra Tabassum, Jin-Mann S. Lin, & William C. Reeves(2009). Electroencephalographic correlates of Chronic Fatigue Syndrome. Behavioral and Brain Functions, 5:43.

References:
Please visit the freely available original article to review the extensive reference list.

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