Evaluating chronotypically tailored light therapy for breast cancer survivors: Preliminary findings on fatigue and disrupted sleep.

More than one-third of cancer survivors experience significant residual symptoms after treatment completion. Fatigue and sleep disruption often co-occur and exacerbate each other. The purpose of this preliminary analysis was to examine the effect of a chronotypically tailored light therapy on fatigue and sleep disruption in female survivors 1-3 years post-completion of chemotherapy and/or radiation for stage I to III breast cancer. The data for this analysis were collected as part of an ongoing two-group randomized controlled trial (NCT03304587). Participants were randomized to receive either bright blue-green light (experimental) or dim red light (control). Light therapy was self-administered using a light visor cap at home. Both groups received 30-min daily light therapy for 14 consecutive days either between 19:00 and 20:00 h (for morning chronotypes) or within 30 min of waking in the morning (for evening chronotypes). Fatigue and sleep quality were self-reported using the Patient-Reported Outcomes Measurement Information System (PROMIS)-Fatigue, PROMIS-Sleep Disturbance, Pittsburgh Sleep Quality Index, and a daily log before (pre-test) and following the light intervention (post-test). Linear mixed model analysis or generalized estimating equations examined group difference overtime adjusting for pre-test scores. No between-group differences were found. However, after adjusting for the baseline fatigue, the experimental group reported significant decreases in fatigue (