Excessive Daytime Sleepiness: Which Evaluation First?

A 40-year-old man with a history of hypertension presents with a primary complaint of feeling tired during the day. He says onset was approximately 2 years ago and the intensity of the feeling has been increasing. He says he feels “weighed down;” that he has to make a special effort to accomplish routine tasks; that his concentration is poor; and that his memory is deteriorating. He describes a sense of “mental fog.” He also has a history of depression, currently treated with fluoxetine, and, when asked about his mood, reports feeling “run down but not depressed.” He reports no sleep difficulties and his weight and appetite have been stable. Thyroid function, blood chemistries and metabolites, and CBC are all within normal limits. The physical examination is unrevealing other than psychomotor slowing.