Post traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) frequently co-occur and these patients often have disrupted sleep. Patients with PTSD are more likely to wake up multiple times a night. Further, autonomic and behavioral components during sleep are consistent with a continued fight or flight defensive state while asleep. This includes higher heart rate, lower parasympathetic tone, and greater likelihood of nightmares. Further supporting this stress response, cortisol levels are inversely related to the proportion of slow wave sleep observed in these patients. PTSD is also associated with higher insomnia severity scores as well as regional neurotransmitter disruptions in systems critical for the regulation of affect. Poor sleep quality is associated with several poor health outcomes that overlap with those that are experienced in PTSD. These include poor cognitive performance and affective lability as well as associations with cardiovascular disease, diabetes and inflammatory diseases including arthritis. Prior research has argued that the etiology of large portion of PTSD related symptoms include disrupted sleep. Effective treatment of sleep problems in this population could have substantial impact on these symptoms and improve quality of life.