The intent of this article is to familiarize dental professionals with the polysomnogram (PSG). The evaluation of patients presenting with sleep disorders is complex, requiring an investigative approach that synthesizes information obtained through a detailed history, a focused physical examination, and appropriate confirmatory testing. The PSG is the only clinical tool that measures multiple physiologic variables to qualitatively and quantitatively evaluate sleep. A proper understanding of the role of the PSG and its measurements and interpretation allows for a proper diagnosis so as to provide an optimal range of treatments for individual patients.