Longitudinal associations between hair cortisol, PTSD symptoms, and sleep disturbances in a sample of firefighters with duty-related trauma exposure.

Several studies have found evidence of altered cortisol levels in patients with posttraumatic stress disorder (PTSD). Based on these findings, it is assumed that these patients may show signs of cortisol dysregulation after trauma. Posttrauma cortisol levels are thus considered a potential biomarker of PTSD. However, longitudinal studies using indicators of long-term cortisol secretion such as hair cortisol concentrations (HCC) are scarce. The current study investigated prospective associations between HCC and PTSD symptoms in a sample of Dutch firefighters taking into account varying levels of work-related trauma severity. In addition, we assessed posttraumatic sleep disturbances as a secondary outcome measure to investigate whether effects generalize to this frequent comorbidity of PTSD. Three hundred seventy-one Dutch firefighters with a mean of 14.01 years of work experience were included in the analyses. Baseline assessment included the collection of hair samples and the measurement of work-related trauma severity, PTSD symptoms, and sleep disturbances. PTSD symptoms and sleep disturbance were re-assessed after six and twelve months. Multilevel analyses indicate a significant positive correlation between HCC and baseline PTSD symptoms in those with average or above-average work-related trauma severity. A similar pattern was evident for posttraumatic sleep disturbances at baseline. Moreover, higher HCC predicted more posttraumatic sleep disturbances after 6 months in participants with above-average work-related trauma severity. No other associations emerged for PTSD symptoms or posttraumatic sleep disturbances at six or twelve months. As such, our study supports the existence of a cross-sectional association between HCC and trauma symptoms, which may vary for different levels of subjective trauma severity. The longitudinal stability of this association should be reinvestigated by future research.

Wakefulness impairs selective consolidation of relevant trauma-associated memories resulting in more frequent intrusions.

Recent studies show that sleep reduces intrusive memories after analog trauma. This effect is assumed to be caused by sleep's impact on memory consolidation. However, the underlying processes of this phenomenon have not been uncovered. Thus, the current study investigates the hypothesis that sleep reduces intrusive memories by supporting the selective consolidation of relevant memories. Seventy-five participants were exposed to traumatic picture stories before nocturnal sleep or wakefulness during daytime. Memory for relevant and irrelevant trauma-associated stimuli was assessed prior to and after the retention period. Consistent with the hypothesis, results demonstrate reduced memory loss for relevant as opposed to irrelevant trauma-associated stimuli after sleep but not after wakefulness. Moreover, an incremental retention benefit for relevant trauma-associated stimuli was negatively correlated with the number of intrusive trauma memories after wakefulness. These results suggest that lack of sleep impairs selective gating of relevant trauma-associated memories, thereby enhancing intrusion development after trauma.