Cognitive behavioural therapy for comorbid insomnia and depression: A randomised, controlled study

Abstract

Insomnia and depression is a common comorbidity and several pilot studies have demonstrated promising results on both conditions by targeting insomnia only. The aim was to investigate the effects of CBT for insomnia (CBT-I) on both sleep and depressive symptoms in a sample with insomnia comorbid with major depression, minor depression or depressive symptoms, using a randomized controlled study. 64 participants were recruited through advertisements and randomised to receive either CBT-I or an active control (relaxation training: RT) in groups during four sessions over seven weeks. Insomnia and depressive severity was measured before, during and after treatment, using Insomnia Severity Index (ISI) and Beck Depression Inventory (BDI- II). We used independent t -tests to investigate if groups were different on symptom severity prior to treatment. There was no difference between CBT-I and RT regarding insomnia severity ( t (55) = 1.30, p = 0.20) or depression severity ( t (53) = −0.77, p = 0.44). Looking at development over time, mixed between-within subjects ANOVAs demonstrated a significant interaction between treatment type and time for both insomnia and depression (ISI: F (2, 54) = 4.96, p = 0.01; BDI: F (2, 58) = 2.80, p = 0.07) meaning that CBT-I meant a larger decrease of both insomnia and depressive severity compared to control treatment. There was also a significant main effect for time with decreasing scores for both groups over time on ISI ( F (2, 52) = 28.86, p = 0.0005) and BDI-II ( F (2, 58) = 7.11, p = 0.002) and a main effect for group on ISI ( F (1, 53) = 9.25, p = 0.01) but not on BDI-II ( F (1, 59) = 0.27, p = 0.60). A six months follow-up assessment is currently conducted and those results will also be presented during the conference. CBT-I was associated with a greater reduction in insomnia and depression severity compared to control treatment. These results show that it is possible to have an effect on both insomnia and depression during a relatively short and cost effective group treatment, targeting insomnia only. This research was supported by grants from Stiftelsen Professor Bror Gadelius Minnesfond, Psykiatrifonden, and the Research Committee of Örebro County Council, Sweden.