Annually, there are about 1.6 million new cases of cancer in the United States, of which breast cancer is the most common. Chemotherapy has long been used in the treatment of breast cancer (as well as other cancers), but it carries the burden of side effects.

A common side effect of chemotherapy is insomnia — the chronic difficulty initiating or maintaining sleep. The treatment leaves more than 75% of patients feeling tired and sluggish, leading to fitful daytime sleep and reduced nighttime sleep.

Healthcare professionals understand the burden of cancer on patients and their loved ones, and researchers are in constant pursuit of better treatment options.

A new study

Out of this desire to improve health outcomes for breast cancer patients comes a large group of scientists who have set out to examine if bright light therapy can feasibly reduce or prevent sleep disruption during chemotherapy.

Thirty-nine women with newly diagnosed breast cancer were placed into one of two groups:

  • Group 1 received morning bright white light for 30 minutes per day.
  • Group 2 received dim red light for 30 minutes per day.

The researchers used two methods to assess the participants’ sleep-wake patterns:

  • “Actigraphy” with wrist-worn devices that measure circadian rhythms using light and movement sensors
  • A sensitive questionnaire-based instrument called the Pittsburgh Sleep Quality Index (PSQI)

The wrist actigraphy lasted for 72 hours and the PSQI was administered before and after the first and fourth cycles of chemotherapy.

When compared with women in the dim red light group, by the end of the fourth cycle of chemotherapy actigraphy readings for those in the bright white light group showed:

  • higher levels or longer durations of nighttime sleep and daytime activity, and
  • lower levels or shorter durations of nighttime sleep disturbances and activation, as well as daytime napping.

Based on PSQI results, while women who received bright white light therapy experienced better sleep quality, their daytime dysfunction grew worse during the fourth cycle of chemotherapy. The researchers noted that women using dim red light also used more sleep medication, which may explain their better sleep quality in the last segment of the study.

Overall, the results of this study indicate that bright white light therapy has promise as an effective treatment option to improve sleep quality for women undergoing chemotherapy for breast cancer.

However, the sample size of 39 participants for this study is relatively small, and further investigation is needed. As the researchers conclude, “Randomized clinical trials in larger samples are needed to confirm these findings.”

 The takeaway

Living with cancer is a stark reality for millions of people and their loved ones. And although advances in cancer therapeutics and treatment are under development, there are still many obstacles to maximize benefit. A primary target remains sleep quality during chemotherapy. Light therapy may provide a key solution, and the preliminary data in this study merit high-priority follow-up.


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Marwan Hamed is a research scientist, public health practitioner and freelance writer for CET.