BACKGROUND Fibromyalgia is characterized by chronic widespread pain and sleep disturbances. Overweight and obesity, which lead to metabolic changes, are additional comorbidities that are rarely explored, although they are highly prevalent in patients with fibromyalgia. METHODS We compared the plasma levels of leptin and acylated ghrelin in 17 women with fibromyalgia (patients) and 16 healthy women (controls) with similar age, anthropometric measurements and levels of physical activity. We also investigated the relationships between these two neuropeptides and sleep and various pain characteristics in patients with fibromyalgia. Anthropometric measurements were recorded, and physical activity levels were assessed using a questionnaire. Pain intensity was measured using visual analogue scales (weekly general and mean pain scores). Sleep was assessed using an accelerometry technique. RESULTS Compared to the control group, the patient group had increased leptin levels (patients: 22.4 ± 10.6 vs. controls: 13.3 ± 17.9 ng/mL; p < 0.01) and decreased acylated ghrelin levels (patients: 126.7 ± 47.8 vs. controls: 183.3 ± 102.2 pg/mL; p = 0.048). The leptin level was not significantly correlated with any of the variables. Acylated ghrelin level was inversely correlated with the weekly mean pain score (r = -0.67, p < 0.01) and the weekly general pain score (r = -0.67, p < 0.01). Multiple regression analysis revealed that the variations in acylated ghrelin levels accounted for 35% of the weekly general pain and 29% of the weekly mean pain variability. CONCLUSIONS These findings indicate that the decreased acylated ghrelin levels in women with fibromyalgia are related to pain intensity.