Sleep disturbances in fibromyalgia syndrome: the role of clinical and polysomnographic variables explaining poor sleep quality in patients

Background: Sleep complaints are one of the most frequent and relevant symptoms that characterize fibromyalgia syndrome (FMS). However, objective sleep disturbances have not been consistently described across FMS studies. It is therefore commonly accepted that FMS patients experience sleep misperception, even though no studies have investigated the contribution of polysomnographic parameters to determine subjective sleep quality in FMS. We aimed to compare sleep variables (polysomnographic parameters and subjective sleep quality) between FMS patients and healthy controls. Furthermore, we also aimed to define the predictors of subjective sleep quality in FMS.

Methods: We performed in-home polysomnography to 99 women (53 FMS patients and 36 healthy controls). We also collected subjective ratings of sleep quality, daytime sleepiness, pain, depression, and anxiety.

Results: Multivariate analysis showed that groups differed in polysomnographic parameters (p = 0.015)--after accounting for age, body mass index, and antidepressant consumption. Specifically, FMS patients exhibited lower sleep efficiency, greater percentage of stage N1 and wakefulness, and more frequent awakenings than controls (p-values < 0.05). Patients also complained about poorer subjective sleep quality (p <0.001). Percentage of time awake (as obtained by polysomnography), depression levels, and antidepressant consumption predicted self-reported sleep quality in FMS patients (adjusted R2 = 0.33, p <0.001).

Conclusions: One night of in-home polysomnography supports the hypothesis that women with FMS show polysomnographic alterations compared to age-matched controls. In addition, the time spent awake is the best predictor of subjective sleep quality, although greater levels of depression and antidepressant consumption might result in exaggerated complaints. These findings contribute to our understanding of FMS symptoms and its management.