Restless legs syndrome

A 50-year-old woman comes to the clinic due to sleeping disturbances for the past 2 months. The patient reports an uncomfortable sensation of the legs that occurs especially at night or during prolonged inactivity. She describes the sensation as a “crawling” and “tingling” sensation which makes her wake up multiple times throughout the night. After waking up, walking and moving her legs provides temporary relief. Medical history is significant for hypertension and diabetes mellitus type 2. The patient’s most recent HbA1C was 7.0% one month ago. Vitals are within normal limits. Physical examination shows bilateral flat foot, for which she uses orthoses. Monofilament examination of the foot is within normal limits. Achilles reflex is 2+ bilaterally. Which of the following is the most likely diagnosis?