 Healthy normal volunteers and patients with RLS between 18 and 80 years of age may be eligible for this study. Patients must have mild to moderate RLS and periodic limb movements. All candidates will be screened with a medical history, physical and neurological evaluations, electromyogram see below, polysomnogram see below, electrocardiogram ECG, and blood and urine tests. They may also have magnetic resonance imaging MRI or computerized tomography CT scans and a chest x-ray. Participants must stop taking all medications prohibited by the study for at least 1 week before the study starts and throughout its duration. 