The Roles of Intrusive Visual Imagery and Verbal Thoughts in Pre-sleep Arousal of Patients with Insomnia Disorder: A Path Model

Insomnia disorder is one of the most common sleep disorders leading to significant distress and lower quality of life. Researchers have proposed that multiple factors such as hyperarousal, conditioning, worry or cortical arousal have roles in predisposition to, initiation, and perpetuation of insomnia disorder. Previously, only few studies investigated the differential effects of intrusive visual imagery and verbal thoughts on pre-sleep arousal or insomnia severity. The aim of the current study was to examine these effects , as well as the moderator role of visual imagery ability on the relationship between intrusive visual imagery and pre-sleep arousal. A path model comprising the variables of intrusive visual imagery, intrusive verbal thoughts, visual imagery ability, pre-sleep arousal, and insomnia severity was tested with 166 participants (Mage = 25.5, SD = 5.26) who met DSM-5 criteria for Insomnia Disorder and had Insomnia Severity Index scores over 8. The results indicated that intrusive visual imagery (β = .45, p < .001), but not intrusive verbal thoughts (β = .16, p = .07), significantly predicted pre-sleep arousal and pre-sleep arousal (β = .46, p < .001) predicted insomnia severity. In addition, the indirect effect of intrusive visual imagery via pre-sleep arousal (IE = .20, p < .001) on insomnia severity was significant. Finally, the moderator role of visual imagery ability on the relationship between intrusive visual imagery and pre-sleep arousal (R2 = .01, F (1, 162) = 2.56, p = .11) was not significant. Intrusive visual imagery plays a more important role in insomnia disorder than intrusive verbal thoughts. Interventions targeting pre-sleep visual imagery may help poor sleepers alleviate their insomnia severity.