Cognitive Behavioural Therapy for Insomnia (CBT-I) to treat depression: A systematic review

Introduction: Major depressive disorder is one of the most commonly diagnosed psychiatric illnesses, and it has a profound negative impact on an individual's ability to function. Up to 90% of individuals suffering from depression also report sleep and circadian disruptions. If these disruptions are not effectively resolved over the course of treatment, the likelihood of relapse into depression is greatly increased. Cognitive Behavioural Therapy for Insomnia (CBT-I) has shown promise in treating these sleep and circadian disturbances associated with depression, and may be effective as a stand-alone treatment for depression. This may be particularly relevant in cases where antidepressant medications are not ideal (e.g. due to contraindications, cost, or treatment resistance). Methods: A systematic literature review was conducted of trials investigating the use of CBT-I to treat depression in adults. Therapy included in-person CBT-I, as well as telehealth and group CBT-I. Results and conclusions: CBT-I presents a promising treatment for depression comorbid with insomnia. In-person therapy has the most supporting evidence for its efficacy, though treatment effects may not be additive with those of antidepressant medications. Insomnia improvement due to CBT-I may mediate the improvement in depressive symptoms. There is less evidence for the use of telehealth, though a stepped-care approach is indicated based on baseline depressive severity. More research on group therapy and telehealth modalities of delivering CBT-I are required before making recommendations.