To demonstrate the superiority of ASP8825 over placebo and the dose response in patients with restless legs syndrome

Three doses of ASP8825 are compared to placebo in efficacy and safety point of view in patients with restless legs syndrome

Inclusion Criteria:

• Patients with RLS, based on the International RSL Study Group Diagnostic Criteria
• History of RLS symptoms at least 15 nights in the prior month or, if on treatment, this frequency of symptoms before treatment was started
• Documented RLS symptoms for at least 4 of the 7 consecutive evenings/ nights during the baseline study period

Exclusion Criteria:

• A sleep disorder (e.g., sleep apnea) that may significantly affect the assessment of RLS
• A history of RLS symptom augmentation or end-of-dose rebound with previous dopamine agonist treatment
• Neurologic disease or movement disorder (e.g., diabetic neuropathy, Parkinson's Disease, Multiple Sclerosis, dyskinesias and dystonias