A 28-year-old female executive has irresistible urges to sleep during the day. She often has episodes of dropping her head, slurred speech, and suddenly dropping things from her hands, all lasting for seconds to minutes. In addition, she frequently has vivid, colorful dreams just before falling asleep. Occasionally, when in certain emotionally charged situations, she feels like her whole body goes limp; however, she remembers everything. Which of the following is the most likely diagnosis?