0946 Examining the Directional Effects of Insomnia, Anxiety, and Depression Symptoms: Results from a Longitudinal Study

Abstract Introduction Although there is evidence supporting high comorbidity rates among insomnia, anxiety, and depression, the temporal relationship among them is less clear. Prior research supports that the onset of depression is often preceded by symptoms of anxiety and insomnia, but the current study is the first to look at the temporal relationship among all three symptoms in an adult sample representative of the general population. Determining the temporal progression of these problems is important for prevention and intervention efforts, in that early treatment for insomnia and anxiety may reduce the risk of developing depression. Methods 2,666 adult participants (Mage = 47.0, 79.0% female, 84.1% white) were recruited for an online study on health, resulting in a nationally representative sample. Well-validated instruments were used to measure symptoms of depression (CES-D), anxiety (STAI), and insomnia (ISI). Data was collected via Qualtrics surveys administered online at two time points (i.e., baseline and follow-up), with assessments conducted twice daily for two weeks in the morning and evening. Auto-regressive cross-lagged models were used to provide the best representation for how these data were collected, and allowed for temporal ordering at every pathway by examining the longitudinal relationship between each variable. Results Auto-regressive cross-lagged models revealed an indirect effect of anxiety symptoms on depression symptoms through insomnia symptoms. Tests of indirect effect were performed in two ways, using both insomnia T1 and insomnia T2 to provide temporal ordering between all three variables. The indirect effect of anxiety T1 on depression T2 through insomnia T1 was significant (β = 0.253, p 0.001). The indirect effect of anxiety T1 on depression T2 through insomnia T2 was also significant (β = 0.265, p 0.001). The almost-identical values for the two tests of indirect effect provide support for the presence of the temporal relationship between these three variables. Conclusion Results support the theory that insomnia may be one mechanism by which individuals with anxiety are at greater risk for developing depression. This is the first study to empirically evaluate a model in which insomnia symptoms explain the indirect effect of anxiety symptoms on depression symptoms in adults. Support (if any) Vargas: K23HL141581