Chronic fatigue, unrefreshing sleep and nocturnal polysomnography

Abstract Background and purpose To investigate the complaint of unrefreshing sleep with study of sleep electroencephalogram (EEG) in patients with chronic fatigue. Patients and methods Fourteen successively seen patients (mean age: 41.1 9.8) who complained of chronic fatigue but denied sleepiness and agreed to participate were compared to 14 controls (33.6±10.2 years) who were monitored during sleep recorded in parallel. After performing conventional sleep scoring we applied Fast Fourier Transformation (FFT) for the delta 1, delta 2, theta, alpha, sigma 1, sigma 2, beta EEG frequency bands. The presence of non-rapid eye movement (NREM) sleep instability was studied with calculation of cyclic alternating pattern (CAP) rate. Two-way analysis of variance (ANOVA) was performed to analyze FFT results and Mann–Whitney U -test to compare CAP rate in both groups of subjects. Results Slow wave sleep (SWS) percentage and sleep efficiency were lower, but there was a significant increase in delta 1 (slow delta) relative power in the chronic fatigue group when compared to normals ( P P =0.04). An increase in respiratory effort and nasal flow limitation were noted with chronic fatigue. Conclusions The complaints of chronic fatigue and unrefreshing sleep were associated with an abnormal CAP rate, with increase in slow delta power spectrum, affirming the presence of an abnormal sleep progression and NREM sleep instability. These specific patterns were related to subtle, undiagnosed sleep-disordered breathing.