Cognitive behavioral therapy for insomnia to treat major depressive disorder with comorbid insomnia: A systematic review and meta-analysis

Objective: Cognitive behavioral therapy for insomnia (CBT-I) has demonstrated efficacy for both insomnia and depression. With a tenfold increase in expected participant numbers, we aimed to update the systematic review and meta-analysis of CBT-I for major depressive disorders (MDD). Methods: Multiple databases were searched up to March 27th 2024 to include all randomized controlled trials examining CBT-I among adults with MDD. The certainty of evidence was evaluated using GRADE. The primary outcome was depression response at post-treatment. Secondary outcomes included insomnia remission and all- cause dropout at post-treatment. Frequentist random-effects pairwise meta-analyses were performed using odds ratio (OR) for dichotomous outcomes. This study was prospectively registered (https://osf.io/kcndz/). Results: Nineteen trials with 4808 randomized participants were identified (mean age, 33.2 [standardized deviation 15.0] years, 73.2 % women. Mean Insomnia Severity Index 19.2 [5.4], median Patient Health Questionnaire-9 16 [range, 8-21]). CBT-I was more beneficial than control conditions for depression response (OR 2.28 [95 % Confidence Interval (CI), 1.67-3.12; GRADE certainty of evidence: moderate), insomnia remission (OR 3.57 [95%CI, 2.48-5.14]: moderate) but could lead to more dropout (OR 1.69 [95%CI, 0.98-2.89]: low). Depression improvement was seen beyond the sleep domain. With a control condition depression response rate of 17 % at post-treatment (median 8 weeks), CBT-I yielded a 32 % response rate (95 % CI, 26 %-39 %). Conclusions: This meta-analysis indicates that CBT-I has significant effects on depressive symptoms beyond the sleep domain among people with MDD. Despite higher dropout rates, these findings suggest CBT-I is an effective treatment for depression comorbid with insomnia.