Gender specificity of the slow wave sleep lost in chronic widespread musculoskeletal pain

Objectives: The majority of patients suffering from musculoskeletal chronic widespread pain (CWP) are females, and they tend to report poor sleep. We tested the hypothesis that the poor sleep of female patients reporting CWP is gender specific for changes in (1) electroencephalograph (EEG) features and (2) heart rate variability (HRV). Methods: Twenty-four normal sleepers were compared to 24 patients with CWP who complained of poor sleep. Patients were referred from general practice and were matched for age (41-47 years) and gender (25 W, 23 M). Sleep variables and spectral EEG activity analyses were performed during 1 night of sleep recording. Time-domain cardiac RR interval and spectral autoregressive analyses were also performed from the same data set. Results: Compared to normal females, female patients with CWP had significantly shorter sleep duration (-68 min), lower sleep efficiency (-9.9%), twice the awakenings and a trend for more periodic limb movements per hour of sleep. Daytime napping was reported by 78% of CWPs. Compared to all controls, females with CWP had significantly less power in the EEG delta band in the first and second non-REM sleep cycle. Although RR interval analysis revealed that CWP patients had a faster heart rate, neither the sympathetic nor sympathovagal analysis reached statistical significance for gender or pain status comparisons. Conclusions: Female CWP patients have shorter sleep duration with many awakenings and lower sleep EEG delta activity without gender difference in HRV. (C) 2010 Elsevier B.V. All rights reserved.