OBJECTIVES: To investigate sleep quality in patients with fibromyalgia (FM) and to analyse the effect of sleep on FM symptoms and quality of life. METHODS: Patients with FM and healthy subjects were recruited to assess their sleep quality, and patients were further assessed for pain, fatigue, depression, psychological stress and quality of life. The patients were divided into a sleep disorder group as measured by the Pittsburgh Sleep Quality Index (PSQI score >7 points) and a group without sleep disorders (PSQI score ≤7 points). Linear regression analysis was used to explore the effect of sleep quality on FM pain controlling for sex and age, and the effect of sleep quality on FM fatigue, depression, psychological stress and quality of life controlling for sex, age and pain. RESULTS: A total of 450 patients and 50 healthy subjects participated in the study. The number of FM patients with sleep disorders was significantly higher than that of healthy subjects (90% vs. 14%, p≤0.001). In addition to the number of pain sites, the levels of pain, fatigue, depression, stress symptoms and quality of life were significantly impaired in FM patients with sleep disorders (p<0.05). In terms of the effects on quality of life assessed with the 36-item short-form health survey, the decrease in mental health was more substantial than the decrease in physical health (B=-12.10 vs. B=-5.40). CONCLUSIONS: Similar to FM patients in other countries and regions, a decrease in sleep quality is also the core symptom of FM patients in China and is significantly correlated with the severity of pain, fatigue, depression and stress symptoms and reduced quality of life, especially with regard to mental health, suggesting that the treatment of this disease should include sleep disorder interventions.