Abstract Introduction Sleep disturbances are common in active duty military personnel and play a key role in the development and maintenance of posttraumatic stress disorder (PTSD). Research indicates that although insomnia and nightmares improve with successful PTSD treatment, they may remain clinically significant. Few previous PTSD studies have assessed sleep disorder constructs using validated instruments. The objectives of this study were to examine the proportion of active duty military personnel seeking treatment for PTSD who reported clinically significant insomnia, nightmares, sleep duration, and excessive daytime sleepiness and to examine the impact PTSD treatment had on these sleep constructs using validated self-report questionnaires. Methods Sleep was evaluated in 223 active duty service members participating in a randomized clinical trial comparing group and individual Cognitive Processing Therapy (CPT) for PTSD. Sleep constructs were assessed using the Insomnia Severity Index (ISI), Trauma-Related Nightmare Survey (TRNS), Self-Assessment of Sleep (SAS), and Epworth Sleepiness Scale (ESS) at baseline and 2 weeks posttreatment. Results At baseline, 82% of participants reported clinically significant insomnia and 75% reported at least 1 moderately severe nightmare per week. Participants reported averaging 4.76 hours of sleep per night, and 65% reported excessive daytime sleepiness. Over the course of PTSD treatment, there were statistically significant improvements in insomnia, nightmares, and excessive daytime sleepiness, but scores remained in clinically significant ranges. Minimal increases were seen in sleep duration. Of the participants who no longer met criteria for PTSD at posttreatment, 50% continued to report clinically significant insomnia, 52% continued to report clinically significant nightmares, and 44% continued to report excessive daytime sleepiness. Conclusion Consistent with previous research, sleep problems persisted for a significant number of service members who completed treatment for PTSD. Insomnia, nightmare, and sleep extension interventions are likely an important part of comprehensive PTSD treatment plans. Support (if any) Funding for this work was made possible by the U.S. Department of Defense through the U.S. Army Medical Research and Materiel Command, Congressionally Directed Medical Research Programs, Psychological Health and Traumatic Brain Injury Research Program awards W81XWH-08-02-109 (Alan Peterson), W81XWH-08-02-0116 (Patricia Resick), W81XWH-10-1-0828 (Daniel Taylor), and W81XWH-08-02-0114 (Brett Litz).