The dream of trauma-related nightmares: Can physiological and subjective within-subjects measures help elucidate sleep-related mechanisms involved in PTSD symptoms?

Abstract

Posttraumatic stress disorder (PTSD) poses significant challenges to individuals, impacting interpersonal relationships, work performance, and overall health outcomes. Treatment can be challenging due to the heterogeneity of PTSD, which is characterized by four distinct symptom clusters: intrusion, avoidance, negative cognition and mood (NegCog), and hyperarousal. Sleep disturbances, inherent to the intrusion and hyperarousal symptom cluster criteria, pervade all clusters. Interventions targeting daytime symptoms offer limited relief for nighttime disturbances, while interventions addressing sleep disruptions appear promising for alleviating both daytime and nighttime symptoms of PTSD. This study aims to elucidate sleep disruption differences across heterogeneous PTSD symptom clusters to inform personalized therapeutic approaches. The data were generously contributed from a larger study in Dr. Edward Pace-Schott's lab examining sleep measures and different prolonged exposure therapy exposure stimuli in a population of trauma-exposed individuals. The variables included in the analysis fall into four categories: (1) sleep architecture, quality, and continuity measures; (2) daytime and sleep measures of arousal; (3) spectral power sleep measures; and (4) self-report assessment measures. These were analyzed in relation to both symptom cluster severity and cluster membership (based on symptom cluster questions in which each participant scored the highest). Additional exploratory analyses using multidimensional scaling (MDS) and investigating relationships between REM density (REMD) and spectral power were conducted.

Despite numerous observed trends, few correlations and pairwise comparisons achieved statistical significance after correcting for multiple comparisons in the main analyses. Significant differences were observed in sleep architecture, quality, and continuity measures. There was a notable association between total sleep time and intrusion cluster scores. In pairwise comparisons, the hyperarousal cluster displayed significantly higher mean scores on the Insomnia Severity Index (ISI) compared to the avoidance and intrusion cluster; the avoidance cluster also had a significantly higher mean ISI scores compared to the intrusion cluster. Both the avoidance and hyperarousal clusters exhibited higher mean Pittsburgh Sleep Quality Index (PSQI) scores than the intrusion cluster. The avoidance cluster also demonstrated significantly longer mean sleep onset latency (SOL) compared to the hyperarousal cluster.

These findings underscore the importance of examining nuanced PTSD-related sleep disruptions from a dimensional, symptom-based perspective. Despite the modest sample size, notable relationships between sleep patterns emerged depending on cluster membership and cluster symptom severity. The findings suggest hyperarousal symptoms may manifest in sleep maintenance issues, while intrusion symptoms may correlate with difficulties initiating sleep. Future research with larger cohorts is warranted to fully discern these associations, potentially paving the way for targeted interventions that ameliorate both daytime and nighttime PTSD symptoms.