A 49-year-old male with a BMI of 38 is referred for evaluation of treatment-resistant depression. He has been treated with adequate trials of sertraline, venlafaxine, and bupropion over the past two years with minimal improvement. He reports persistent fatigue, excessive daytime sleepiness, difficulty concentrating, irritability, and low motivation. He falls asleep unintentionally during meetings and while driving. His wife reports loud snoring with witnessed apneic episodes where he stops breathing for several seconds before gasping. He wakes unrefreshed despite sleeping 8-9 hours nightly and reports morning headaches. On examination, he has a Mallampati class IV airway, a neck circumference of 18 inches, and a crowded oropharynx. His Epworth Sleepiness Scale score is 17 (normal <10). Which of the following is the most appropriate diagnostic consideration?