A subject will be defined at Day 42 as a Responder if the International Restless Legs Syndrome Severity Scale (IRLSS) score is ≤10 or if the IRLSS score is >10 with a Clinical Global Impression-Improvement (CGI-I) score of much or very much improvement and the subject does not request further treatment for RLS. A subject will be defined as a treatment Non-Responder if neither of these criteria are met.