Persistence of poor sleep predicts the severity of the clinical condition after 6 months of standard treatment in patients with eating disorders

•Patients with eating disorders frequently experience poor sleep.•Poor sleep predicts severity of eating disorders through the mediation of depression.•Poor sleep persistence predicts ED symptoms' severity after 6 months of treatment.•Poor sleep persistence predicts worse clinical conditions after 6 months of treatment.

Clinical evidence suggests that eating disorder (ED) patients experience poor sleep even if they rarely complain of it. However, direct empirical evidence supporting this relationship is still sparse. In order to provide direct evidence, poor sleep, severity of the ED symptoms and depression were obtained in 562 ED patients at treatment admission (T0). For 271 patients out of them, data were also available after 6 months of standard treatment (T1). Results evidence that at T0 poor sleep predicts severity of ED symptoms through the mediation of depression. Persistence of poor sleep at T1 directly predicts the severity of the ED symptoms both directly and through the mediation of depression. These findings suggest that the treatment of ED may benefit from addressing poor sleep since its presence and persistence increase comorbidity and attrition to the standard treatment.