An integrated model of chronic trauma-induced insomnia.

Insomnia is the most commonly reported symptom of posttraumatic stress disorder (PTSD), with at least 70% of patients with PTSD reporting disturbed sleep. Although posttraumatic insomnia has traditionally been conceptualized as a consequence of PTSD, it is the most likely symptom to not remit following otherwise successful PTSD treatment. This suggests that the relationship between PTSD and insomnia is more complex, such that they likely share underlying pathological mechanisms and that factors non-specific to PTSD maintain chronic trauma-induced insomnia. Although several theories and hypotheses have been presented to explain the relationship between PTSD and insomnia, neurobiological and psychological models have not been integrated, thereby limiting their comprehensiveness and abilities to inform effective intervention. Further, existing models have not addressed how acute trauma-induced insomnia becomes chronic. The present review examined models of PTSD and insomnia separately, as well as existing theorized mechanisms of their co-morbidity. The distinct characteristics of trauma-induced insomnia were also reviewed and presented to describe the unique clinical presentation of trauma-induced insomnia. Review and integration of the literature were used to propose an integrated model of chronic trauma-induced insomnia informed by a neuropsychobiological framework. Clinical implications and future research directions are presented and discussed.