Cognitive Behavioral Therapy for Insomnia Reduces Depression in Cancer Survivors

Study Objectives: The current archival analyses examine the direct and indirect effects of cognitive behavioral therapy for insomnia (CBT-I) on depression in cancer survivors. Methods: We report on 67 cancer survivors from a 2 x 2 randomized controlled trial of CBT-I and armodafinil for insomnia, after collapsing across the noneffective study medication conditions (armodafinil/placebo) to create CBT-I (yes/no). Depression and insomnia were assessed before, during the 7-week CBT-I intervention, at postintervention, and 3 months later by the Patient Health Questionnaire and the Insomnia Severity Index, respectively. Results: Mean depression at baseline for all participants was 6.44 (standard error=0.41, range 0-15). Paired t tests showed that depression improved from baseline to postintervention by 48% (P<.001) in the CBT-I group versus 15% (P=.016) in the non-CBT-I group. Analysis of covariance controlling for baseline found that participants receiving CBT-I had significantly less depression at postintervention (effect size=-0.62; P=.001), compared to those who did not receive CBT-I. These benefits were maintained at the 3-month follow-up. Spearman rank correlations showed that changes in insomnia severity from baseline to postintervention were significantly correlated with concurrent changes in depression (r=.73; P<.001). Path analysis revealed that improvement in depression was mediated by improvement in insomnia severity (P<.001). Conclusions: Our findings provide preliminary support that in cancer survivors, CBT-I reduces depression via improvement in insomnia. Further, this reduction in depression remained stable 3 months after completing CBT-I. This suggests that a CBT-I intervention has a meaningful effect on depression.