Effects of internet-delivered cognitive-behavioral therapy for insomnia (iCBT-I) on fatigue in breast cancer survivors: exploring changes in sleep outcomes as mediators

Robert Hugh Zachariae, Ali Amidi, Malene Damholdt, Cecilie Dorthea Rask Clausen, Jesper Ovesen Dahlgaard, Holly Lord, Frances Thorndike, Lee Ritterband

Research output: Contribution to conference without a publisher/journalPaperResearchpeer-review


Background and purpose: Internet-delivered cognitive-behavioral therapy for insomnia (iCBT-I) has been shown efficacious in improving sleep and reducing fatigue in breast cancer survivors. Our aim was to explore changes in sleep outcomes as mediators of the effect of iCBT-I on fatigue.
Methods: 255 breast cancer survivors with sleep disturbances were randomized to iCBT-I or waitlist control and completed online measures of insomnia severity (ISI), global sleep quality (PSQI), and fatigue (FACIT-F) at baseline (T1), postintervention (T2), and follow-up (T3) together with online sleep diaries over two-week periods at T1 and T2. Indirect effects of changes in sleep outcomes on changes in fatigue were explored with regression-based mediation analyses.

Results: Statistically significant indirect effects on T1-T2 changes in fatigue were found for T1-T2 changes in ISI (-0.48; 95%CI: -0.70 – -0.29), PSQI (-0.33; 95%CI: -0.48 – -0.21), and diary-based subjective sleep quality (SQ) (-0.27; 95%CI: -0.45 – -0.11). T1-T2 changes ISI scores also mediated T2-T3 changes in fatigue (-0.29; 95%CI: -0.50 – -0.08). No indirect effects were found of improvements in the diary-based outcomes of sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST), early morning awakenings (EMA), time in bed (TIB), or sleep efficiency (SE).

Conclusions: In the sample of breast cancer survivors, the effects of iCBT-I on fatigue appeared to be driven by changes in the subjective sleep outcomes of insomnia severity and sleep quality, whereas changes in sleep diary-based outcomes, e.g., SOL, WASO, and TST, appeared unrelated to improvements in fatigue.
Original languageEnglish
Publication date31 Oct 2018
Publication statusPublished - 31 Oct 2018
EventThe 20th International Psycho-Oncology Society World Congress - Hong Kong, Hong Kong, China
Duration: 31 Oct 20182 Nov 2018


ConferenceThe 20th International Psycho-Oncology Society World Congress
LocationHong Kong
CityHong Kong


  • health, nutrition and quality of life

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