Customized light therapy may improve sleep quality for breast cancer survivors. Both cancer and its treatments can disrupt the body’s circadian rhythms, leading to fatigue and sleep disturbances. In fact, as many as one third of cancer survivors experience sleep problems.

Horng-Shiuann Wu, PhD, of the College of Nursing at Michigan State University, and colleagues looked at the effect of tailored light therapy on fatigue and sleep disruption in women who had undergone chemotherapy or radiation for breast cancer one to three years earlier.

The women were randomly assigned to receive light therapy at home using bright blue-green light, which has been shown to reset circadian rhythms, or dim red light as a control. Women with a morning chronotype (“larks”) received light exposure in the evening, while those with an evening chronotype (“owls”) were exposed to light within a half hour after waking up in the morning.

After receiving light therapy for two weeks, women exposed to bright light reported a significant decrease in fatigue and sleep disturbances. The bright-light group had better sleep quality, with a shorter delay in falling asleep and longer sleep duration. Unexpectedly, sleep disturbances also decreased in the control group exposed to dim light. “Properly timed light exposure may optimize the therapeutic effect and can be the key for successful light therapy,” the researchers concluded.