Effect of insomnia treatments on depression: A systematic review and meta-analysis

Insomnia is frequently co-morbid with depression, with a bidirectional relationship between these disorders. There is evidence that insomnia-specific interventions, such as cognitive behavioral therapy for insomnia, may lead to improvements in depression. The purpose of this systematic review and meta-analysis is to determine whether treatment of insomnia leads to improved depression outcomes in individuals with both insomnia and depression.We conduct a systematic review and meta-analysis to explore the effect of treatment for insomnia disorder on depression in patients with both disorders.Three thousand eight hundred and fifteen studies were reviewed, and 23 studies met inclusion criteria. Although all of the studies suggested a positive clinical effect of insomnia treatment on depression outcomes, most of the results were not statistically significant. Although the interventions and populations were highly variable, the meta-analysis indicates moderate to large effect size (ES) improvement in depression as measured with the Hamilton Depression Rating Scale (ES = -1.29, 95%CI [-2.11, -0.47]) and Beck Depression Inventory (ES = -0.68, 95%CI [-1.29, -0.06]).These results support that treating insomnia in patients with depression has a positive effect on mood. Future trials are needed to identify the subtypes of patients whose depression improves during treatment with insomnia-specific interventions, and to identify the mechanisms by which treating insomnia improves mood.