Guest editorial

Sleep and post-traumatic stress disorder: A roadmap for clinicians and researchers

Problematic smartphone use (PSU) and sleep disorders (SD) are common public health problems among college students. While previous cross-sectional studies have found a relationship between PSU and SD, the causal direction of this relationship remains unclear. This study aims to examine the longitudinal changes of PSU and SD during the COVID-19 pandemic, determine the causal relationship between them, and identify confounding factors that affect this association.

The study sample consisted of 1186 Chinese college students (47.7% male) with a mean age of 18.08 years. Participants completed the Smartphone Addiction Scale - Short Version (SAS-SV) and the Pittsburgh Sleep Quality Index (PSQI) at both baseline and follow-up surveys, conducted one year apart. The cross-lagged panel model (CLPM) was used to examine the causal relationship between PSU and SD, stratified by gender and duration of daily physical activity. The fixed effect panel regression was used to confirm the findings of CLPM.

The results of the CLPM analysis showed a significant bidirectional relationship between PSU and SD for the overall sample, which was consistent with the fixed effects model findings. However, subgroup analyses revealed that the bidirectional association disappeared among males or those who engaged in daily physical activity for more than 1 h.

Our study shows a significant bidirectional association between PSU and SD, with variations across gender and daily physical activity levels. Encouraging physical activity may serve as a potential intervention to disrupt the bidirectional association between PSU and SD, which has important implications for public health strategies aimed at reducing the negative consequences of PSU and SD.

In Posttraumatic Stress Disorder (PTSD), fear and anxiety become dysregulated following psychologically traumatic events. Regulation of fear and anxiety involves both high-level cognitive processes such as cognitive reattribution and low-level, partially automatic memory processes such as fear extinction, safety learning and habituation. These latter processes are believed to be deficient in PTSD. While insomnia and nightmares are characteristic symptoms of existing PTSD, abundant recent evidence suggests that sleep disruption prior to and acute sleep disturbance following traumatic events both can predispose an individual to develop PTSD. Sleep promotes consolidation in multiple memory systems and is believed to also do so for low-level emotion-regulatory memory processes. Consequently sleep disruption may contribute to the etiology of PTSD by interfering with consolidation in low-level emotion-regulatory memory systems. During the first weeks following a traumatic event, when in the course of everyday life resilient individuals begin to acquire and consolidate these low-level emotion-regulatory memories, those who will develop PTSD symptoms may fail to do so. This deficit may, in part, result from alterations of sleep that interfere with their consolidation, such as REM fragmentation, that have also been found to presage later PTSD symptoms. Here, sleep disruption in PTSD as well as fear extinction, safety learning and habituation and their known alterations in PTSD are first briefly reviewed. Then neural processes that occur during the early post-trauma period that might impede low-level emotion regulatory processes through alterations of sleep quality and physiology will be considered. Lastly, recent neuroimaging evidence from a fear conditioning and extinction paradigm in patient groups and their controls will be considered along with one possible neural process that may contribute to a vulnerability to PTSD following trauma.

There has been growing interest in the interrelations among traumatic event exposure, posttraumatic stress disorder (PTSD), and sleep problems. A wealth of research has examined the associations among these factors and there is an emerging literature focused on how sleep problems relate to both traumatic event exposure and PTSD across time. The current review provides a detailed analysis of studies pertaining to the temporal patterning of sleep problems and traumatic event-related factors (e.g., traumatic event exposure, PTSD) and draws conclusions regarding the current state of this literature. Research coalesces to suggest (1) exposure to a traumatic event can interfere with sleep, (2) PTSD is related to the development of self-reported sleep problems, but evidence is less clear regarding objective indices of sleep, and (3) limited evidence suggests sleep problems may interfere with recovery from elevated posttraumatic stress levels. Future research now needs to focus on understanding mechanisms involved in these patterns to inform the prevention and treatment of comorbid sleep problems and PTSD.