Abstract
Insomnia and depression are highly comorbid conditions that show a complex, bidirectional relationship. This study examined whether cognitive–behavioral therapy for insomnia (CBT-I) delivered by a therapist compared with self-help CBT-I (written materials only) reduces insomnia and depression severity in individuals with comorbid insomnia and depression. A total of 41 participants (18–64 years; 25 females) with comorbid depression and insomnia, treated with antidepressants for at least 6 weeks, were randomized to receive 4 sessions of either CBT-I or self-help CBT-I over 8 weeks. Insomnia (Insomnia Severity Index [ISI]) and depression (Beck Depression Inventory-II [BDI-II]) were assessed at baseline, following each session, and at 3-month follow-up. Secondary outcomes were sleep quality and duration (actigraphy and diaries), anxiety, fatigue, and daytime sleepiness. Compared with self-help CBT-I, BDI-II scores in the CBT-I group dropped by 11.93 (95% confidence interval [CI] [6.60, 17.27], p < .001) more points, and ISI scores dropped by 6.59 (95% CI [3.04, 10.15], p = .001) more points across treatment. At 3-month follow-up, 61.1% of CBT-I participants were in clinical remission from their insomnia and depression, compared with 5.6% of the self-help group. Conclusions: CBT-I administered by a therapist produced significant reductions in both insomnia and depression severity posttreatment and at follow-up, compared with a control condition in which participants received only written CBT-I material. Targeting insomnia through CBT-I is efficacious for treating comorbid insomnia and depression, and should be considered an important adjunct therapy for patients with depression whose symptoms have not remitted through antidepressant treatment. (PsycInfo Database Record (c) 2025 APA, all rights reserved)