Study objectives: To determine the associations between deployment in support of the wars in Iraq and Afghanistan and sleep quantity and quality.
Design: Longitudinal cohort study
Setting: The Millennium Cohort Study survey is administered via a secure website or US mail.
Participants: Data were from 41,225 Millennium Cohort members who completed baseline (2001-2003) and follow-up (2004-2006) surveys. Participants were placed into 1 of 3 exposure groups based on their deployment status at follow-up: nondeployed, survey completed during deployment, or survey completed postdeployment.
Measurements and results: Study outcomes were self-reported sleep duration and trouble sleeping, defined as having trouble falling asleep or staying asleep. Adjusted mean sleep duration was significantly shorter among those in the deployed and postdeployment groups compared with those who did not deploy. Additionally, male gender and greater stress were significantly associated with shorter sleep duration. Personnel who completed their survey during deployment or postdeployment were significantly more likely to have trouble sleeping than those who had not deployed. Lower self-reported general health, female gender, and reporting of mental health symptoms at baseline were also significantly associated with increased odds of trouble sleeping.
Conclusions: Deployment significantly influenced sleep quality and quantity in this population though effect size was mediated with statistical modeling that included mental health symptoms. Personnel reporting combat exposures or mental health symptoms had increased odds of trouble sleeping. These findings merit further research to increase understanding of temporal relationships between sleep and mental health outcomes occurring during and after deployment.
Keywords: Millennium Cohort; Sleep; deployment; mental health; veterans.