Introduction <p>This study investigates the prevalence of sleep disorders among patients with fibromyalgia syndrome (FMS) in French pain clinics, addressing a gap between international and national data. It also aims to describe associated factors such as quality of life (QoL), pain, daily functioning, and psychological symptoms.</p> Methods <p>The study included 508 patients with an average age of 46 ± 10&#xa0;years. Patients attending a specialized chronic pain center, either at their initial consultation or within the first year of follow-up, completed online self-administered questionnaires. Questionnaire were related to sleep disorders, pain, anxiety and QoL.</p> Results <p>In this sample, sleep disorders were highly prevalent among French patients with FMS (95.3% with Pittsburgh Sleep Quality Index (PSQI) &gt; 5; 69.9% with PSQI &gt; 10). More than 13% were identified as being at high risk for sleep apnea, and 60% reported symptoms suggestive of restless leg syndrome (RLS). The median scores on the Brief Pain Inventory were 6.0 (Q1: 5.3–Q3: 7.0) for pain severity and 5.9 (Q1: 4.7–Q3: 7.1) for pain interference. The Hospital Anxiety and Depression Scale revealed a median anxiety score of 11.0 (Q1: 9.0–Q3: 15.0). Regarding the impact of FMS on daily life, the median score on the Fibromyalgia Impact Questionnaire was 59.0 (Q1: 44.0–Q3: 71.0).</p> Conclusions <p>In contrast to French estimates, this study revealed a high prevalence of sleep disorders among patients with FMS, underscoring a gap in care. A substantial proportion of patients were at high risk for RLS and a clinically relevant risk for sleep apnea. Anxiety, depression, and reduced QoL were also highly prevalent, reflecting the complex and multifactorial burden of FMS. These findings highlight the need for a comprehensive, patient-centered approach that includes targeted management of sleep disturbances as a core component of fibromyalgia care.</p>