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

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.