Comparison of sleep structure in patients with fibromyalgia and healthy controls

Sleep disturbances such as nonrestorative sleep and nighttime awakenings play a crucial role in fibromyalgia (FMS). Pain and sleep disturbances show a bidirectional relationship which affect outcomes in FMS. This study aims to compare sleep structures between patients with fibromyalgia and healthy controls.

We evaluated subjective and objective sleep structures of 33 patients with fibromyalgia and 34 healthy controls using the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and polysomnography. Student's T test, chi-square, discriminant analysis, the Kruskal-Wallis, and Mann-Whitney U test were used for statistical analysis.

Patients with FMS reported poorer sleep quality than controls (p = 0.003). Polysomnography data showed patients with FMS exhibited a greater number of awakenings (p = 0.01), more arousals (p = 0.00), higher arousal index (p = 0.00), greater apnea hypopnea index (p = 0.03), and less N1 sleep (p = 0.02) than healthy controls. The discriminant analysis revealed that number of arousals, arousal index, and N1 sleep were able to distinguish patients with FMS from healthy controls with 78.5% accuracy. Twelve of the 33 patients with FMS were diagnosed with obstructive sleep apnea syndrome (OSAS). When we excluded patients with OSAS, a statistically significant difference was maintained.

Our findings may explain the deterioration of subjective sleep, symptoms as unrefreshing sleep, fatigue, and pain in patients with FMS. Despite similar clinical manifestations, patients with FMS should be evaluated for OSAS due to treatment differences. The role of sleep alterations in the clinical manifestation and severity of FMS suggest that effective treatments to improve sleep quality may lead to more effective management of FMS.