Dissociative experiences are increasingly conceptualized as a transdiagnostic phenomenon. Sleep-related processes—particularly nightmares, which are affectively intense and REM-related—have been implicated in dissociation through pathways such as emotion regulation difficulties and insomnia severity. This study, therefore, examined whether emotion regulation difficulties and insomnia severity mediate the association between nightmare distress and dissociative experiences.

Adults from Tehran ( N  = 378) completed the Nightmare Distress Questionnaire (NDQ), Dissociative Experiences Scale–II (DES-II), Difficulties in Emotion Regulation Scale–16 (DERS-16), and Insomnia Severity Index (ISI). Structural equation modeling (SEM) evaluated whether emotion regulation and insomnia severity mediated the nightmare–dissociation association; indirect effects were tested with 2,000 bootstrap resamples.

The structural equation model showed acceptable fit. Nightmare distress strongly predicted dissociation and was also associated with both emotion regulation difficulties and insomnia severity. Emotion regulation difficulties, in turn, had a small but significant association with dissociation, whereas insomnia severity did not. Mediation analysis indicated a significant indirect effect through emotion regulation but not through insomnia. The model explained 46% of the variance in dissociation.

This study provides novel evidence that difficulties in emotion regulation partly explain the association between nightmare distress and dissociative experiences, whereas insomnia severity contributes little to this link. These findings highlight the primacy of affective and REM-related processes in dissociation, underscoring the need for future longitudinal and experimental research using objective sleep measures.