Posttraumatic stress disorder (PTSD) is common following the experience of a natural disaster and sleep disturbance is an important influence on its course in adults, but little research is available examining sleep and PTSD in youths. This study's objective was to evaluate the role of sleep disturbance and the developmentally influenced factor of fear of sleeping alone in the maintenance of posttraumatic stress (PTS) symptoms in youths. Deidentified data of 191 Hurricane Katrina survivors ages 8 to 15 were used in this study. We found cross-sectional relationships of sleep disturbance and fear of sleeping alone with PTS symptom severity. Longitudinal analysis also indicated that general sleep disturbance at 24 months (T1) was predictive of PTS symptoms severity at 30 months (T2) even after adjusting for PTS symptom severity at T1, age, sex, and continued disrepair to the home. These results have implications for intervention strategies among youth exposed to traumatic events.