Study Objectives: The efficacy of cognitive behavioral therapy for insomnia (CBT-I) has been suggested for insomnia concomitant with depression, but its impact on quality of life (QoL) has not been adequately evaluated. The study aimed to determine which aspects of QoL could be affected by CBT-I and how any changes in QoL were mediated by changes in insomnia and depression.
Methods: We conducted a 4-week randomized controlled trial with 4-week follow-up in outpatient clinics in Japan. Thirty-seven patients with DSM-IV diagnosis of major depressive disorder concomitant with chronic insomnia were randomly assigned to the treatment-as-usual (TAU) alone arm or the TAU with brief behavioral therapy for insomnia (TAU plus psychotherapy) arm using modified CBT-I consisting of 4 weekly individual sessions. We evaluated QoL using norm-based scoring of the Short Form-36 at baseline and at 8 weeks. We also examined associations between QoL subscales and remission in insomnia or depression while controlling for baseline scores of the entire sample.
Results: We tested group effects while controlling for baseline scores. TAU plus psychotherapy resulted in significantly better scores on physical functioning (p = 0.006), social functioning (p = 0.002), and mental health (p = 0.041) subscales than TAU alone at 8 weeks. Patients with either remitted insomnia or depression showed higher QoL scores than non-remitted patients; scores approximated those within the normal range.
Conclusions: For patients with insomnia in depression, adding CBT-I to TAU can produce substantive benefits in some aspects of QoL.