The aim of this randomised controlled assessor-blinded trial was to examine the effect of cognitive behavioural therapy for insomnia on sleep variables and depressive symptomatology in outpatients with comorbid insomnia and moderate to severe depression. Forty-seven participants were randomized to receive one weekly session in 6 weeks of cognitive behavioural therapy for insomnia or treatment as usual. The intervention was a hybrid between individual and group treatment. Sleep scheduling could be especially challenging in a group format as patients with depression may need more support to adhere to the treatment recommendations. The primary outcome measure was the Insomnia Severity Index. Secondary measures were sleep diary data, the Dysfunctional Beliefs and Attitudes about Sleep Questionnaire, the Hamilton Depression Rating Scale, and the World Health Organization Questionnaire for Quality of Life and polysomnography. Compared to treatment as usual, cognitive behavioural therapy significantly reduced the insomnia severity index (mean ISI 20.6 to 12.1, p = 0.001) and wake after sleep onset (mean 54.7 min to 19.0 min, p = 0.003) and increased sleep efficiency (mean SE 71.6 to 83.4, p = 0.006). Total sleep time and sleep onset latency were not significantly changed. The results were supported by analyses of the other rating scales and symptom dimensions. In conclusion, cognitive behavioural therapy for insomnia as add-on to treatment as usual was effective for treating insomnia and depressive symptoms in a small sample of outpatients with insomnia and major depression. ClinicalTrials.gov Identifier: NCT02678702.
Keywords: dysfunctional beliefs and attitudes about sleep; insomnia severity index; mood disorder; nonpharmacological treatment; sleep disorder; sleep medicine.