Effects of Chronotype-tailored Bright Light Intervention on Symptoms and Quality of Life in Breast Cancer Survivors

PURPOSE: Bright light therapy holds promise for reducing common symptoms, e.g., fatigue, experienced by individuals with cancer. This study aimed to examine the effects of a chronotype-tailored bright light intervention on sleep disturbance, fatigue, depressive mood, cognitive dysfunction, and quality of life among post-treatment breast cancer survivors. METHODS: In this two-group randomized controlled trial (NCT03304587), participants were randomized to receive 30-min daily bright blue-green light (12,000 lux) or dim red light (5 lux) either between 19:00–20:00 h or within 30 min of waking in the morning. Self-reported outcomes and in-lab overnight polysomnography sleep study were assessed before (pre-test) and after the 14-day light intervention (post-test). RESULTS: The sample included 30 women 1–3 years post-completion of chemotherapy and/or radiation for stage I to III breast cancer (mean age = 52.5 ± 8.4 years). There were no significant between-group differences in any of the symptoms or quality of life (all p > 0.05). However, within each group, self-reported sleep disturbance, fatigue, and depressive mood, and quality of life-related functioning showed significant improvements over time (all p < 0.01); the extent of improvement for fatigue and depressive mood was clinically relevant. Polysomnography sleep findings showed that number of awakenings significantly decreased (p = 0.011) among participants received bright light, while stage 2 sleep significantly increased (p = 0.015) among participants received dim-red light. CONCLUSION: The findings provide some evidence to support using chronotype-tailored light therapy to manage sleep disturbance, fatigue, depressive mood in post-treatment breast cancer survivors. The unexpected symptom improvements among dim-red light controls remain unexplained and requires further investigation. CLINICALTRIALS.GOV IDENTIFIER: NCT03304587 Study was registered on October 19, 2017.