A circadian and app-based personalized lighting intervention for the reduction of cancer-related fatigue.

Lighting interventions can mitigate fatigue by promoting circadian rhythmicity. We test whether individualized, wearable-based lighting interventions delivered via a mobile app reduce cancer-related fatigue in a randomized controlled trial with 138 breast cancer, prostate cancer, and hematopoietic stem cell transplant patients. Participants are randomized to tailored lighting intervention or control. The primary endpoint is PROMIS fatigue 4a at trial end, with secondary endpoints including change in daily fatigue, sleep, anxiety, depression, physical function, and overall health. Fatigue T-scores at week 11 do not differ between groups but decrease significantly from week 1 to week 11 (3.07 points, p = 0.001) in the intervention group, with a significant final-week treatment effect (p = 0.014). Daily fatigue, anxiety, sleep disturbance, and physical function improve within intervention. Further studies are needed to see if these results generalize in broader cancer care. The trial is registered at ClinicalTrials.gov (trial registration number: NCT04827446).