A variety of pharmacologic agents have been studied to treat CRF, but there is insufficient evidence to recommend their use. The most promising non-pharmacologic interventions -- exercise and cognitive-behavior therapy (CBT) -- have shown equally modest effects. The proposed study focuses on a promising new intervention for CRF, using systematic light exposure (SLE), consisting of a daily 30-minute exposure to as much as 10,000 lux of light from a commercially available light box. Study collaborator, Ancoli-Israel and her colleagues have successfully piloted this line of research with breast cancer patients undergoing chemotherapy.