A 58-year-old woman presents to her primary care physician with a 2-year history of an unpleasant “creepy-crawly” sensation deep in her calves. This occurs almost every evening while she is sitting and watching television. The feeling creates a powerful, irresistible urge to move her legs. She finds relief only by walking around her living room, but the sensation returns soon after she sits down again. The symptoms are now severe enough to make falling asleep difficult, causing significant daytime fatigue and impairing her mood. Her past medical history is notable for uterine fibroids with heavy menstrual bleeding, which resolved after menopause approximately 8 years ago. She currently takes escitalopram 10 mg daily for mild anxiety and a daily multivitamin. She drinks one cup of coffee in the morning and occasionally a glass of wine with dinner. She denies any weakness, numbness, or tingling in her legs and has no history of joint pain or swelling. Her temperature is 37.0^oC, blood pressure is 125/73 mm Hg, heart rate is 72 bpm, and respirations are 16/min.