Rating of daytime and night-time symptoms in RLS: validation of the RLS-6 scale of restless legs syndrome / willis-ekbom disease

•The International Restless Legs Scale (IRLS) is the main scale for rating the severity of restless legs syndrome/Willis–Ekbom disease (RLS/WED).•The Restless Legs Syndrome-6 Scale (RLS-6) is an additional scale for rating the severity of RLS that provides further information on RLS severity not captured by the IRLS.•In the current validation study, the RLS-6 seems to be an acceptable, reliable, precise, valid, and responsive instrument for the assessment of RLS severity in a specific and pragmatic manner.•At present, we view the RLS-6 not as a replacement for the IRLS but as a supplement, as each scale provides information not captured by the other.