Objective:The aim was to study the effect of stable treatment with Sodium Oxybate (SO) on nocturnal REM sleep behavior disorder (RBD) and REM sleep without atonia (RSWA) that severely affected children with type 1 narcolepsy (NT1.Methods:Nineteen NT1 children and adolescents (nine females; mean age 12.5±2.7, mean disease duration: 3.4±1.6 years) underwent neurological investigations and video-polysomnography (v-PSG) at baseline and after three months of stable treatment with SO.v-PSG was independently analysed by two sleep experts, in order to rate RBD episodes. RSWA was automatically computed by means of the validated REM sleep atonia index (RAI).Results:Compared to baseline, RAI significantly improved (p< 0.05) and complex movements during REM sleep were remarkably reduced after stable treatment with SO. Compared to baseline, children also reported improvement in clinical complaints and showed a different nighttime sleep stage architecture.Conclusions:RBD and RSWA improved after treatment with SO, pointing to a direct role of the drug in modulating motor control during REM sleep.