A 25-year-old male presents to the neurology clinic reporting episodes of suddenly falling to the ground without losing consciousness, triggered by excitement or surprise, over the past year. He also admits to irresistible urges to nap during the day, even while driving, and recalls waking up unable to move for a few seconds several times in the past month. A sleep study is planned. Which diagnostic test is most appropriate to confirm the suspected diagnosis of narcolepsy in this patient?
