Insomnia and sleep apnea in the entire population of US Army soldiers: Associations with deployment and combat exposure 2010-2019, a retrospective cohort investigation

This retrospective cohort study examined clinically diagnosed insomnia and sleep apnea and analyzed associations with deployment and combat exposure in active-duty soldiers (n = 1,228,346) from 2010 to 2019. Retrospective data were obtained from the Soldier Performance, Health, and Readiness database. Overseas soldier deployments peaked in 2010, decreasing thereafter as soldiers were withdrawn from Iraq and Afghanistan. From 2010 to 2012 insomnia incidence increased at a rate of 6.7 cases/1000 soldier-years, then decreased after 2012 at 5.3 cases/1000 soldier-years. Sleep apnea increased 2010-2016 at 1.9 cases/1000 soldier-years and generally declined thereafter. Risk of insomnia increased with deployment (hazard ratio = 1.51; 95% confidence interval = 1.49-1.52) and combat exposure (hazard ratio = 1.15; 95% confidence interval = 1.13-1.17). Risk of sleep apnea was increased by deployment (hazard ratio = 1.89; 95% confidence interval, 1.86-1.92) and combat exposure (hazard ratio = 1.09; 95% confidence interval, 1.07-1.11). Most relationships remained after accounting for other factors in multivariable analyses, except that the association between sleep apnea and combat exposure was reduced (hazard ratio = 0.94; 95% confidence interval = 0.92-0.97). Insomnia risk decreased in the period nearly in parallel with a reduction in the number of deployments; nonetheless deployment and combat exposure increased insomnia risk in the period examined. Risk of sleep apnea increased in the period and was related to deployment but not combat exposure after accounting for demographics and comorbid conditions. Despite reductions in insomnia incidence and a slowing in sleep apnea incidence, sleep disorders remain highly prevalent, warranting continued emphasis on sleep-disorder screening and improving the soldier sleep habits.