Hyperarousal as a key predictor in longitudinal trajectories of insomnia symptoms up to 10 years post-deployment in military personnel

Abstract: STUDY OBJECTIVES: Insomnia is a common sleeping disorder in military personnel and is linked to the development and maintenance of other mental health symptoms. How insomnia symptoms develop long-term, up to 10 years following deployment and what pre-deployment risk factors underpin this development is not yet clear. METHODS: A cohort of Dutch military personnel (n = 846, PRISMO cohort) deployed to Afghanistan was studied from pre-deployment to 10-years post-deployment. Longitudinal trajectories of insomnia symptoms were explored with a latent class growth analysis. Both linear and nonlinear predictive modeling were performed to assess which pre-deployment demographic, psychological, and biological variables predicted insomnia symptoms. RESULTS: We identified five trajectories of insomnia symptoms in military personnel from pre- to 10 years post-deployment: resilient sleepers (44%), recovery from pre-deployment insomnia (15%), insomnia symptoms, minor decrease following deployment (22%), minor increase (8%), and incident insomnia since deployment (11%). These groups did not differ in demographic variables. Both linear and nonlinear models could distinguish trajectories with post-deployment insomnia symptoms from resilient sleepers based on pre-deployment variables with hyperarousal as top predictor. CONCLUSIONS: Our findings demonstrate that insomnia symptoms among military personnel are mainly affected by deployment and stable over a 10-year period post-deployment. Predictive modeling can help identify vulnerable subpopulations, though additional measurements might improve accuracy. Early interventions may prevent chronicity of the symptoms and the development of other mental health symptoms. Statement of Significance The long-term development of insomnia symptoms remains understudied, especially in military personnel, despite its links to other mental health issues. Here, we report distinct trajectories of insomnia symptoms of military personnel up to 10 years post-deployment. Predictive models, using pre-deployment psychological and biological factors and deployment experiences, enabled us to distinguish post-deployment trajectories, with pre-deployment hyperarousal emerging as top predictor of vulnerability. Future research should focus on external validation of the findings, enhancing predictive power with additional variables and exploring early interventions for prevention of chronicity of insomnia symptoms and associated mental health conditions following military deployment.