Abstract
There has been a growing interest in determining the antecedents of the significant associations between dissociative symptomatology and sleep. The aim of this study was to investigate the mediation effect of a tendency to elicit uncontrollable and excessive worry on the relationship between dissociation and poor sleep quality among non-shift working health staff. Eighty-five participants with a mean age of 31.19 ±7.14 (ranging from 18 to 54) involved within the study. The Penn State Worry Questionnaire (PSWQ), Dissociative Experiences Scale (DES), Pittsburgh Sleep Quality Index (PSQI) and a demographic questionnaire were administered. Mediation regression models were utilized to evaluate direct and indirect associations between worry, dissociation and sleep quality after controlling for age, gender, marital status, education, prior psychiatric disorders, familial loading and time spent watching TV series in a week. Regression models indicated that direct dose-response relationship between dissociative symptomatology and sleep quality was not statistically significant. However, indirect effects of dissociative symptoms though pathological worry were substantial. More specifically, we found that the DES total, absorption/imaginative involvement and dissociative amnesia had significant indirect effects on poor sleep quality via excessive worry as measured by the PSWQ. We concluded that dissociative symptoms are indirectly associated with sleep through negative repetitive thoughts such as pathological worry. Therefore, new generation therapeutic approaches particularly mindfulness therapy should be considered in the first-line treatments of sleep disturbance.

Key words: : Dissociation; Repetitive thoughts; Negative thinking; Affect regulation; Sleep disorders; Avoidance model; Sleep-dissociation