Stress Disorders, Posttraumatic

Post-traumatic stress disorder (PTSD) is a common consequence of combat that can result in trauma-related hyperarousal and sleep disturbances. Poor sleep, one of the most common complaints in Veterans with PTSD, can be distressing, impair concentration and memory, and contribute to physical health conditions, such as metabolic syndrome, inflammation, and cardiovascular disease. The orexin neuropeptide system underlies both sleep and stress reactivity. Suvorexant, a drug that reduces orexin, improves sleep in civilians, but has not yet been tested in Veterans with PTSD. This study will test whether suvorexant can improve sleep disturbances and PTSD symptoms in Veterans. Suvorexant may benefit Veterans by improving sleep quickly while also reducing PTSD symptoms over the long term, and with fewer side effects that were common in previous medications used to treat these conditions. Improving Veterans' sleep and PTSD symptoms could lead to better emotional and physical well-being, quality of life, relationships, and functioning.