Ecological momentary assessment of daily affect, stress, and nightmare reports among combat-exposed Veterans.

Background: Research primarily in civilian samples supports bidirectional relations between daytime factors and trauma-related nightmare (TRN) reports. This study tested the relations of daytime negative affect and event-related stress with nightly occurrence and characteristics of TRNs in a sample of Veterans with and without posttraumatic stress disorder (PTSD). Methods: We studied 27 U.S. combat-exposed Veterans who completed prompts across seven days of an ecological momentary assessment protocol, assessing daytime negative affect and event-related stress. Each morning they also reported whether they had a TRN and, if so, the level of disturbance and vividness. Results: Over 100 morning reports were collected. Approximately half of this sample (55%) reported at least one TRN across the study week, with TRNs reported only by participants with current PTSD. In multilevel logistic regression models, higher average negative affect was associated with greater odds of having TRNs. While negative affect and event-related stress on a given day were not prospectively associated with TRNs later that night, a TRN occurrence was associated with greater next-day negative affect and event-related stress. Conclusion: In contrast to findings found in civilian populations, daytime negative affect and stress during the day were not associated with subsequent TRN occurrences in this Veteran sample. Instead, there was evidence for a cumulative effect of negative affect on TRN occurrence, potentially driven by experiencing TRNs. Therefore, targeting TRNs specifically could have a positive impact on reducing this self-maintaining nightmare cycle.