The role of negative urgency and sleep-related repetitive negative thinking in the relationship between anxiety sensitivity and insomnia: A serial mediation model

Insomnia is a prevalent condition associated with various physiological and psychological disorders, characterized by difficulties in falling asleep, maintaining sleep, and experiencing impairment during the day due to insufficient sleep. While anxiety sensitivity (AS), impulsivity, intrusive thoughts, and worry have been individually studied in terms of their relationship with insomnia, their interplay in predicting individual differences in insomnia remains underexplored. This study investigates the relationship between AS and insomnia severity (IS), with a focus on negative urgency (NU) and sleep-related repetitive negative thinking (sRNT) as serial mediators. Cross-sectional data from 299 participants (65.2% female; aged 18 to 65, M = 33.17, SD = 11.18) were collected through convenience sampling via social media platforms. Participants completed self-report measures of negative urgency, anxiety sensitivity, sleep-related repetitive thinking, and insomnia severity. The results revealed that AS significantly and positively correlated with NU, and sRNT. All study variables, except NU, had significant positive correlations with IS. However, NU and sRNT did not significantly and serially mediate the association between AS and IS. Notably, sRNT fully mediated the relationship between AS and IS. These findings suggest that individuals with high AS may engage in harmful, persistent thinking about their sleep, contributing to increased insomnia severity. The results advance our understanding of the underlying insomnia development and maintenance processes, highlighting AS and sRNT as vulnerability factors for this condition. Keywords: insomnia, anxiety sensitivity, sleep-related repetitive negative thinking, negative urgency