The objective of this trial is to demonstrate that rotigotine (SPM 936) is effective in subjects with idiopathic RLS based on the PLMI (Periodic Limb Movements Index)(PLMs/total time in bed) as measured by polysomnography (PSG). The primary variable is the reduction of PLMI at the end of the Maintenance Period compared to Baseline. PLMI data will be obtained from PSGs.