Patients may complain of daytime drowsiness associated with a painful musculoskeletal disorder, but these complaints regard an activity of daily living (ADL) and do not result in a separate sleep impairment rating. This article focuses on sleep impairment resulting from documented nervous system dysfunction or sleep apnea. Because the accuracy and reliability of sleep testing are critical for the proper diagnosis and impairment rating of a sleep disorder, sleep testing should be completed at a center certified by the American Academy of Sleep Medicine. In both the fifth and sixth editions of the AMAGuides to the Evaluation of Permanent Impairment (AMA Guides), neurologically based sleep disorders are rated using Chapter 13, and sleep apnea is rated using Chapter 5. The AMA Guides, Sixth Edition, does provide a rating value of up to 3% whole person impairment for sleep apnea related impairment, but the fifth edition does not provide any numerical rating value. A sleep disturbance not related to neurologically based dysfunction or apnea should be considered according to its effects on ADLs for the primary pathology identified or diagnosed. Expert understanding of sleep disorders is crucial, as is the specialized experience of a credentialed sleep laboratory. Subjective questionnaires can be used to screen for sleep disorders or excessive daytime sleepiness, but formal sleep studies are necessary to confirm any diagnosis and to provide an objective basis to assess permanent impairment.