Bedtime repetitive negative thinking moderates the relationship between psychological stress and insomnia.

Research suggests that psychological stress is associated with insomnia, but there is limited research on vulnerabilities that might amplify this association, particularly in college students. Based on a sample of 507 undergraduates, the current study demonstrates that the observed positive correlation between self-perceived stress and insomnia severity is moderated by the tendency to engage in repetitive negative thinking (RNT) at bedtime. Additionally, separate analyses of those who scored below/above the threshold for insomnia (non-insomniacs vs. insomniacs) revealed that the interaction between stress and these negative bedtime cognitions differed qualitatively between the two groups. In insomniacs, the stress-insomnia relationship was dampened for those with lower levels of bedtime RNT, but amplified for those with higher levels. For non-insomniacs, the stress-insomnia relationship was stronger for those with minimal bedtime RNT, while higher levels of bedtime RNT appeared to overshadow this association. To develop a better understanding of the contribution of stress and RNT to clinically relevant levels of insomnia, future studies should take into account the dissimilar patterns of moderation seen in non-insomniacs and insomniacs, either through prospective screening or separate analyses. Findings from the current study suggest that insomnia treatments that can simultaneously reduce stress and address bedtime RNT may be optimal.