A 22-year-old woman presents to discuss fatigue. She can fall asleep easily, including falling asleep last week at a red light while driving. She also describes a transient paralysis that happens whenever she hears something funny or has an orgasm. Findings on her physical examination are normal. Which of the following is the most appropriate next step in evaluation? Echocardiogram Electroencephalography Polysomnogram Psychiatry referral Thyroid-stimulating hormone level