Randomized study on the efficacy of cognitive-behavioral therapy for insomnia secondary to breast cancer, part II: Immunologic effects

Abstract

Purpose: Cross-sectional studies suggest that clinical insomnia is associated with immune down-regulation. However, there is a definite need for experimental studies on this question. The goal of this randomized controlled study was to assess the effect of an 8-week cognitive-behavioral therapy (CBT) for chronic insomnia on immune functioning of breast cancer survivors. Previous analyses of this study showed that CBT was associated with improved sleep and quality of life, and reduced psychological distress. Patients and Methods: Fifty-seven women with chronic insomnia secondary to breast cancer were randomly assigned to CBT (n = 27) or to a waiting-list control condition (WLC; n = 30). Peripheral-blood samples were taken at baseline and post-treatment (and postwaiting for WLC patients), as well as at 3-, 6-, and 12-month follow-up for immune measures, including enumeration of blood cell counts (ie, WBCs, monocytes, lymphocytes, CD3+, CD4+, CD8+, and CD16+/ CD56+) and cytokine production (ie, interleukin-1-beta [IL-1β] and interferon gamma [IFN-γ]). Results: Patients treated with CBT had higher secretion of IFN-γ and lower increase of lymphocytes at post-treatment compared with control patients. Pooled data from both treated groups indicated significantly increased levels of IFN-γ and IL-1β from pre- to post-treatment. In addition, significant changes in WBCs, lymphocytes, and IFN-γ were found at follow-up compared with post-treatment. Conclusion: This study provides some support to the hypothesis of a causal relationship between clinical insomnia and immune functioning. Future studies are needed to investigate the clinical impact of such immune alterations. © 2005 by American Society of Clinical Oncology.