Dr. Finnerty examines the controversy and science related to VA disability nexus letters for sleep apnea secondary to posttraumatic stress disorder (PTSD) and other psychological conditions like depression and anxiety. Learn about why nexus letters are sometimes needed in sleep apnea secondary to PTSD disability claims. Dr. Finnerty addresses common reasons why claims are denied and the research supporting a nexus. The book was written both for Veterans interested in researching VA disability benefits for sleep apnea secondary to PTSD and the professionals tasked with helping to determine whether a Veteran's sleep apnea is secondary to PTSD. It is a VA disability claim book related to the medical evidence needed in Veterans' disability ratings.