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Defining the Occurrence and Influence of Alpha-Delta Sleep in Chronic Fatigue Syndrome

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ABSTRACT

Background

Patients with chronic fatigue syndrome (CFS) present a disordered sleep pattern and frequently undergo polysomnography to exclude a primary sleep disorder. Such studies have shown reduced sleep efficiency, a reduction of deep sleep, prolonged sleep initiation, and alpha-wave intrusion during deep sleep. Deregulation of the 2-5A synthetase/RNase L antiviral pathway and a potential acquired channelopathy are also found in a subset of CFS patients and could lead to sleep disturbances. This article compiles a large sleep study database on CFS patients and correlates these data with a limited number of immune parameters as it has been thought that RNase L could be associated with these sleep disturbances.

Methods

Forty-eight patients who fulfilled 1994 Centers for Disease Control and Prevention criteria for CFS underwent extensive medical evaluation, routine laboratory testing, and a structured psychiatric interview. Subjects then completed a complaint checklist and a two-night polysomnographic investigation. RNase L analysis was performed by gel electrophoresis using a radiolabeled 2′,5′-oligoadenylate trimer. Basic descriptive statistical parameters were calculated.

Results

Patients experienced a prolonged sleep latency, showed a low sleep efficiency index, and had a low percentage of slow wave sleep. The present alpha-delta intrusion correlated with anxiety; no correlations appeared, however, between alpha-delta sleep and immunologic parameters, including RNase L.

Conclusions

The main findings are 1) validation of sleep latency problems and other sleep disturbances as already suggested by several authors; 2) alpha-delta intrusion seems associated with anxiety; and 3) elevated RNase L did not correlate with alpha-delta sleep.

Section snippets

Recruitment of CFS Patients

Study subjects were recruited from the outpatient fatigue clinic, Vrije Universiteit Brussels between October and February 2003. Generally, patients are referred by their general practitioner to the outpatient fatigue clinic. To fulfill the 1994 CDC criteria for CFS, clinically evaluated, unexplained, persistent, or relapsing chronic fatigue that is of new or definite onset should result in a substantial reduction in previous levels of occupational, educational, social, or personal activities.2

Subjects

Forty-eight patients were included in this study, of which 19 were male (40%) and 29 were female (60%). The mean age of the patients was 45 years (±10.46 years). The mean number of years the patients experienced symptoms was 8.98 (±7.71 years). The mean scores on the immune parameters are presented in Table 2. None of the immune variables fell outside their reference score.

Rnase L

The mean RNase L was 4.47 (±0.71) with a median of 2.80. The deregulation of the RNase L pathway can be quantified by

Discussion

Sleep architecture variables demonstrated significantly different sleep onset latency and sleep disturbances in CFS patients (Table 4). Because of the resemblance between the CFS patients used by Fischler et al13 and Fossey et al15 and our CFS population, their results may apply to our sample, although no healthy control group was used. Similar results were already reported by several other authors, such as Whelton et al10 and Stough and Withers.14 CFS patients present less sleep continuity.

Acknowledgments

Our Department would like to thank Kim Borremans in collecting the appropriate data and Nancy Reichenbach for her help in academic writing.

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