A 23-year-old female college student is referred to the psychiatric mental health nurse practitioner (PMHNP) by her school counselor. She reports feeling exhausted several times per week, to the point of being unable to stay awake. She has fallen asleep in class more than once. She also reports periods of "zoning out" for a few seconds. During these episodes, it feels like her muscles "give out," but she doesn't fall asleep. This also occurs several times a week. The woman says these symptoms have been occurring since the beginning of the semester, 3 months ago. Which diagnosis best describes this clinical picture?