Predictors of insomnia symptoms and nightmares among individuals with post‐traumatic stress disorder: an ecological momentary assessment study
Typically, sleep disturbances among those with PTSD are thought to be triggered and maintained initially by PTSD symptoms. For example, many studies have found a link between PTSD symptom severity and insomnia symptoms or nightmares (Short et al., 2014). Relatedly, trauma‐related nightmares can cause or exacerbate insomnia symptoms (DeViva et al., 2004; Gellis et al., 2010; Krakow et al., 2000). However, many prior studies have relied upon cross‐sectional examinations, despite the significant day‐to‐day variation in symptoms many with PTSD experience (Possemato et al., 2012). Assessing daily levels of PTSD could inform us as to whether increased PTSD symptoms during the day lead to poorer sleep that night. Furthermore, those with PTSD may begin to fear sleep due to its association with nightmares (Pruiksma et al., 2014), which could further disrupt sleep onset. We considered fear of sleep a PTSD‐related variable rather than an insomnia‐related one due to its specificity with PTSD‐related insomnia (i.e. we would not expect an individual with insomnia disorder without PTSD to fear sleep per se, as we might expect individuals with PTSD to do so). Despite the potential importance of fear of sleep in insomnia symptoms, it has not been examined as a predictor of insomnia symptoms and nightmares among a clinical sample of those with PTSD. Finally, depression is a common comorbidity with PTSD, and has also been linked to poor sleep and nightmares (DeViva et al., 2004; Gellis et al., 2010), but has only been examined as cross‐sectional correlates of sleep disturbance.
In addition to these PTSD‐specific pathways to sleep disturbance, it is commonly believed that insomnia develops its own maintenance factors over time (Talbot et al., 2014). For example, individuals with PTSD‐related sleep disturbance probably develop dysfunctional beliefs about sleep (DBAS), which serve to amplify distress related to insomnia and increase trouble with sleep onset and maintenance (Morin et al., 2007). Furthermore, it is likely that individuals begin to engage in insomnia‐related safety behaviours (e.g. going to bed early to allow enough time to fall asleep, sleeping in if one has difficulty falling asleep), which are used to cope with the symptoms of insomnia, but paradoxically increase difficulty falling asleep. Theoretically, maintenance factors such as these cause insomnia to persist regardless of PTSD status (DeViva et al., 2004). The role of these insomnia‐specific maintenance factors is supported further by research showing that cognitive–behavioural therapy for insomnia (CBT‐I), which targets these maintenance factors, is effective in treating insomnia among those with PTSD without modifications and with only small effects on PTSD symptoms themselves (Talbot et al., 2014). However, no prior research has tested whether insomnia‐specific factors play a role in sleep disturbances among those with PTSD.
Overall, current models of sleep disturbance in PTSD emphasize both PTSD‐related factors, as well as insomnia‐specific factors in sleep disturbances among those with PTSD. It is important to note that this is a somewhat artificial distinction, as insomnia and nightmares are symptoms of PTSD and thus, by definition, PTSD‐related.