The Association between Insomnia and Anxiety Symptoms in a Naturalistic Anxiety Treatment Setting

Objective/Background: Few studies have examined the relationship between insomnia and anxiety treatment outcomes in naturalistic settings. Furthermore, prior studies typically examine insomnia within a single anxiety diagnosis without accounting for the high overlap between disorders. Here we investigate the association between insomnia and multiple anxiety disorders over a course of cognitive behavioral treatment (CBT) in a naturalistic treatment setting. Participants: Insomnia was assessed in 326 patients seeking treatment at a clinic specializing in CBT for anxiety. Methods: Multilevel modeling was used to investigate whether insomnia moderated reductions in anxiety symptoms. A cross-lagged analysis tested for bidirectional effects between insomnia and anxiety. Multiple regression was used to investigate the relationship between insomnia and anxiety while controlling for the other anxiety disorders and depression. Results: While there was a significant reduction in insomnia during treatment in all anxiety disorders, the majority of the most severe patients remained in the clinical range at post-treatment. Baseline insomnia did not significantly moderate anxiety outcomes, suggesting that patients with high or low levels of insomnia will do equally well in CBT for anxiety. The bidirectional effect between insomnia and anxiety did not reach significance. Additionally, posttraumatic stress disorder, generalized anxiety disorder, and panic disorder were associated with the greatest endorsement of insomnia, after controlling for the overlap between disorders. Conclusions: Sleep problems may persist after anxiety treatment, suggesting that CBT for insomnia may be warranted during or after a course of CBT for anxiety. Importantly, baseline insomnia does not impede anxiety reduction during CBT.