Objective: To examine the role of insomnia as a mediator between worrying and mental health and whether the association between worrying and insomnia is moderated by the levels of exercise frequency.
Methods: A cross-sectional online survey was conducted during the fourth wave of the COVID-19 outbreak in Hong Kong (n = 988). Participants' insomnia, psychological distress, and exercise frequency were evaluated. A mediation analysis was performed to examine the direct effect of COVID-19 worries and their indirect effect through insomnia on psychological distress.
Results: A significant indirect effect of COVID-19 worries through insomnia was found on psychological distress (beta = 0.18, SE = 0.02, 95% CI = 0.14-0.22, p < .001). The significant index of moderated mediation supported the moderating effect of exercise frequency on the indirect effect of COVID-19 worries on psychological distress (IMM = 0.06, SE = 0.02, 95% CI = 0.02-0.10, p = .006). The conditional indirect effects of insomnia on psychological distress were significant in individuals with mean and higher exercise frequency but not in those with lower exercise frequency.
Conclusion: COVID-19 worries increased psychological distress through the worsening of sleep, and such an array of COVID-19 worries on insomnia was moderated by exercise frequency. Engaging more frequent exercise could reduce insomnia in people with less COVID-19 worries.