Abstract
Introduction
Military personnel are at an increased risk for suicide compared to the general population, making it important to develop a deeper understanding of which factors contribute to this elevated risk. Given that suicidal ideation (SI) is one of the strongest predictors of suicide attempts, understanding factors that underlie SI may improve prevention efforts. Insomnia and depression both serve as independent risk factors for SI, and therefore the aim of this study was to examine the extent to which depressive symptoms moderate the association between insomnia and SI.
Methods
Data were obtained from the All Army Study of the Army Study to Assess Risk and Resilience in Servicemembers (STARRS). Soldiers (n=21,450) completed questions related to suicidal ideation (5 items), depressive symptoms (9 items), and insomnia (5 items) based on symptom presence in the past 30 days. Items in each domain were summed to create a total severity score. GEE models using a negative binomial linking function were conducted to examine the impact of depression, insomnia, and their interaction on SI.
Results
Both depression (χ2 =117.56, p<0.001) and insomnia (χ2=11.79, p=0.0006) were found to have significant main effects on SI, and there was a significant interaction effect (χ2=4.52, p=0.0335). Follow up simple effects revealed that insomnia was no longer significantly associated with SI when depression severity was low, but was associated with SI in the presence of greater depression severity (χ2=2.91, p=0.0882).
Conclusion
In a large sample of Army soldiers, depression significantly moderated the association between SI and insomnia, such that insomnia seems to amplify the effects of depression on SI. These findings highlight the importance of addressing insomnia severity as a mean of reducing SI in those with depression, potentially allowing for intervention prior to a suicide attempt.
Support (if any)
Perlis: K24AG055602 & R01AG041783. This publication is based on public use data from Army STARRS (Inter-university Consortium for Political and Social Research, University of Michigan- http://doi.org/10.3886/ICPSR35197-v1), funded by U.S. NIMH-U01MH087981.
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