Purpose: During chemotherapy, women with breast cancer not only experience poor quality of life (QOL), they also have little exposure to bright light, which has been shown to be associated with depression, fatigue, and poor sleep in other chronic illnesses. This study examined whether increased light exposure would have a positive effect on QOL.
Methods: Thirty-nine women with stage I-III breast cancer scheduled to receive ≥ 4 cycles of chemotherapy were randomized to a bright white light (BWL, n = 23) or dim red light (DRL, n = 16) treatment group. Data were collected before (baseline) and during cycles 1 and 4 of chemotherapy. Light was administered via a light box (Litebook(®), Ltd.). QOL was assessed with the Functional Assessment of Cancer Therapy-Breast (FACT-B) and the Functional Outcomes of Sleep Questionnaire (FOSQ).
Results: Compared with baseline, the DRL group demonstrated significant decline in QOL during the treatment weeks of both cycles (all ps < 0.02), whereas the BWL group had no significant decline (all ps > 0.05). Mixed model analyses revealed that there was a group-by-time interaction for FOSQ at the treatment week of cycle 4, and this interaction was mediated by fatigue.
Conclusion: The data suggest that increased exposure to bright light during chemotherapy may prevent the decline in QOL via preventing the increase in fatigue.