A 19-year-old college student presents to the clinic with excessive daytime sleepiness that has been worsening over the past year. He reports falling asleep suddenly during lectures despite getting 7–8 hours of sleep at night. He also describes sudden episodes of muscle weakness triggered by laughter, lasting a few seconds. Additionally, he has experienced vivid, dream-like hallucinations when falling asleep and occasional episodes where he wakes up but cannot move. His neurological exam is unremarkable. Which of the following is the most likely cause of this patient’s condition?
