Examining the Efficacy of Bright Light Therapy on Cognitive Function in Hematopoietic Stem Cell Transplant Survivors

Lisa M. Wu*, Heiddis B. Valdimarsdottir, Ali Amidi, Kathryn J. Reid, Sonia Ancoli-Israel, Katrin Bovbjerg, Rina S. Fox, Lauren Walker, Amreen Matharu, Erin T. Kaseda, John P. Galvin, Kehinde Adekola, Gary Winkel, Frank Penedo, William H. Redd

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Patients who have undergone hematopoietic stem cell transplant (HSCT) may experience cognitive impairment that can persist after treatment. Several studies have shown that bright light therapy may improve cognition, potentially due to its effects on the circadian system via brain regions that respond preferentially to light. In this double-blind randomized controlled trial, the efficacy of bright light therapy on cognition was examined in HSCT survivors. Forty-seven HSCT survivors at an urban hospital in the United States were screened for mild cognitive impairment, randomized to either bright white light (BWL) or comparison dim red light (DRL) conditions using a block randomization approach, and instructed to use their assigned light box every morning upon awakening for 30 min for 4 weeks. Assessments occurred at baseline, the end of the second week of the intervention, the end of the intervention, and at follow-up (8 weeks later). The primary outcome was objective cognitive function as measured by a global composite score on neuropsychological tests. Secondary outcomes included cognitive performance in individual domains, self-reported cognitive function, fatigue, sleep and sleep quality, and circadian rhythm robustness. Repeated-measures linear mixed models for both objective and self-reported cognitive function indicated significant main effects for time (ps < 0.05) suggesting significant improvements in both conditions over time. Time by light condition interaction effects were not significant. Models focused on secondary outcomes yielded no significant effects. Both BWL and DRL groups demonstrated significant improvements in objective cognitive and self-reported cognitive function over time, but there was no hypothesized effect of BWL over DRL nor associations with circadian rhythm robustness. Therapeutic effects of both light conditions, practice effects, and/or placebo effects may account for the findings. Trial registration: ClinicalTrials.gov

Original languageEnglish
Pages (from-to)471-483
Number of pages13
JournalJournal of Biological Rhythms
Issue number5
Publication statusPublished - Oct 2022

Bibliographical note

Funding Information:
We thank all of our participants and our research colleague, Diana Buitrago, at Northwestern University Feinberg School of Medicine, without whom this study would not have been possible. This work was supported by the National Cancer Institute (NCI) of the National Institutes of Health (Grant K07CA184145 [PI: L.M.W.]). L.M.W.’s effort was also supported by the European Union Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie grant agreement no. 754513 and the Aarhus University Research Foundation. R.S.F.’s effort was supported by the NCI of the National Institutes of Health (Grant K08CA247973 [PI: R.S.F.]). REDCap is supported at Northwestern University Feinberg School of Medicine by the Northwestern University Clinical and Translational Science (NUCATS) Institute and was supported, in part, by the National Institutes of Health’s National Center for Advancing Translational Sciences (Grant UL1TR001422).

Publisher Copyright:
© 2022 The Author(s).

Other keywords

  • cancer
  • circadian rhythms
  • cognitive impairment
  • fatigue
  • hematological malignancies
  • hematopoietic cell transplant
  • light therapy
  • sleep
  • Hematopoietic Stem Cell Transplantation/adverse effects
  • Humans
  • Survivors
  • Cognition
  • Circadian Rhythm
  • Phototherapy
  • Sleep


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