The Interplay Between Emotion Dysregulation and Repetitive Thoughts in Insomnia Disorder: The Impact of Worry, Rumination and <scp>REM</scp> Sleep Instability

While previous research has identified emotional dysregulation and repetitive thinking as contributors to insomnia, the interplay between these factors remains unclear. Building upon data previously collected in our laboratory, this exploratory study extends prior findings by examining the mediating role of rumination, worry and rapid eye movement (REM) sleep instability in the relationship between emotional dysregulation and the functional impact of insomnia and depressive symptoms, aiming to generate hypotheses about the psychological and neurophysiological mechanisms linking these constructs. Using the same cohort of 23 patients with insomnia disorder and 23 matched healthy sleepers, participants underwent overnight polysomnography and completed validated questionnaires assessing emotional dysregulation, worry, rumination and the functional impact of insomnia. Novel mediation models were used to examine whether worry, rumination and REM sleep instability mediated the link between emotional dysregulation and daytime consequences of insomnia. Compared to controls, individuals with insomnia showed significantly greater emotional dysregulation, rumination and worry. Mediation analysis indicated that rumination, but not worry, significantly mediated the relationship between emotional dysregulation and daytime consequences of insomnia. Furthermore, higher scores on the dimension 'difficulties in distracting with emotions' were associated with increased REM sleep instability, which also mediated the effect of emotional dysregulation on daytime consequences of insomnia. These findings highlight the crucial role of rumination in sustaining the functional impact of insomnia and suggest that interventions targeting repetitive negative thinking and emotional regulation may improve sleep outcomes.