Effect of Increased Light Exposure on Fatigue in Breast Cancer

Overview

Patients treated with chemotherapy complain of poor sleep, fatigue and depression. In addition, chemotherapy disrupts the body's internal "biological clock", which may make sleep, fatigue and depression all worse. Women with breast cancer undergoing chemotherapy are not exposed to much bright light and this may also contribute to the disruption of their body clock, because bright light is necessary for a strong biological clock. One of the easiest ways to strengthen the biological clock is by increasing bright light exposure. The correct timing of the light exposure will help the women feel more alert during the day.

Patients treated with chemotherapy complain of poor sleep, fatigue and depression. Our preliminary research suggests that these symptoms may all be related, that chemotherapy disrupts circadian rhythms which may exacerbate the poor sleep and fatigue and that during chemotherapy, women are not exposed to much bright light which likely also contributes to the disruption of rhythms. One of the easiest circadian rhythms to measure is sleep/wake activity and the easiest way to synchronize this rhythm is with bright light treatment. It is well established that bright light exposure will make rhythms more robust, and the correct timing of the light exposure will have an alerting effect. We hypothesize that after bright light treatment compared to dim light treatment during three cycles of chemotherapy: fatigue (measured by the Multidimensional Fatigue Symptom Inventory), depression (measured by the Center of Epidemiological Studies-Depression scale), functional outcome scores (measured by the Functional Outcome of Sleep Questionnaire and by the Functional Assessment of Cancer Therapy-Breast), and sleep measures (measured by actigraphy, e.g., total sleep time, total wake time, bouts of sleep, napping) will all be improved. We also hypothesize that circadian rhythms (measured by actigraphy) will be more robust and more synchronized. The aims are to examine the effect of bright light treatment on subjective measures of fatigue, mood and functional outcome experienced during chemotherapy, to examine the effect of bright light treatment on the quality and quantity of sleep during chemotherapy, to examine the effect of bright light treatment on sleep/wake rhythms during chemotherapy. Women with breast cancer stages I-III scheduled to begin chemotherapy will be recruited. Wrist actigraphy data (for the measurement of sleep/wake activity) will be collected for three consecutive days and nights immediately preceding chemotherapy and questionnaire data (fatigue, mood, quality of life, functional outcome, sleep) will be collected during this same time period. Half the women will be randomized to receive bright light and the other half to dim red light as a control. Daily bright light or dim light treatment will be administered during cycles 2, 3 and 4 of chemotherapy and all measures (actigraphy and questionnaires) will be repeated during the first and last weeks of cycle 1 and cycle 4 chemotherapy. If bright light can improve sleep rhythms and fatigue, then the quality of life of these women is likely to improve.