Inclusion Criteria:  a Veteran of the U.S. military or Reserve/National Guard member at least 18 years of age have an AHI 5 per hour experienced trauma that occurred in childhood or adulthood; at least one month post-trauma have current DSM-5 diagnoses of SUD via SCID-SUD module with a minimum 20 days of substance use in the last 90 days (Timeline Follow-back) Full PTSD diagnosis via clinician administered PTSD scale are literate in English are on the PTSD track of the SARRTP unit are capable of giving informed consent  Exclusion Criteria:  have central sleep apnea (AHI >=5 and > 50% central apneas) arrives on the SARRTP unit already using a PAP device (Veteran's previously diagnosed with OSA, but not using PAP therapy will be eligible) the SARRTP medical staff advises against the study based on medical history and physical examination; d) history of severe cognitive impairment (via MOCA < 26) history of psychosis or mania independent of substance use will be excluded because the presence of these disorders can impede therapy progress