A 49-year-old man is evaluated for a 2-year history of poor sleep with associated daytime fatigue and sleepiness that often interfere with his performance at work. He recorded a sleep diary, which reveals difficulty with sleep initiation and multiple awakenings throughout the night. He has no other physical symptoms that affect his sleep, and his partner does not notice him snoring or gasping. Physical examination, including vital signs, is normal. Which of the following is the most appropriate next step in management?
A. Cognitive behavioral therapy
B. Diphenhydramine
C. Melatonin
D. Mirtazapine
E. Zolpidem