Healio Interviews.

Disclosures: Ancoli-Israel, Davis, Mao and Zhou report no relevant financial disclosures.
February 22, 2022
3 min read

Insomnia in cancer survivors: A common, potentially harmful issue


Healio Interviews.

Disclosures: Ancoli-Israel, Davis, Mao and Zhou report no relevant financial disclosures.
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Insomnia is an all too familiar modern problem and can negatively impact various aspects of health.

Along with other vulnerable populations, patients affected by cancer are particularly susceptible to insomnia. Although survivors may experience some relief from insomnia once active cancer treatment is concluded, sleeplessness often lingers into survivorship. The American Cancer Society estimates that insomnia continues among nearly 40% of cancer survivors up to 5 years after diagnosis.

According to The American Cancer Society: Insomnia is estimated to continue among nearly 40% of cancer survivors up to 5 years after diagnosis.
Data derived from the American Cancer Society. Study finds sleep problems persist in cancer survivors. Published Feb. 3, 2020. Accessed Jan. 24, 2022.

“There are probably a million and one reasons why a cancer survivor might be more likely to have insomnia than a noncancer survivor,” Eric Zhou, PhD, faculty member in the division of sleep medicine and assistant professor of pediatrics at Harvard Medical School, said in an interview with Healio. “Survivors, by definition, have endured a lot, and the things they have survived often constitute multiple insults to their system. A survivor might have done fine through the initial phases of treatment, but then at some point, something happened to tip them over the edge. It’s not always a clear participating event — sometimes it is just a small straw that breaks that camel’s back.”

Healio spoke with experts about causes of insomnia among cancer survivors and how it can affect their physical and mental health.

Common causes

The cause of insomnia in a particular cancer survivor may be as unique and individual as the survivor himself or herself. According to Jun J. Mao, MD, MSCE, chief of integrative medicine service at Memorial Sloan Kettering Cancer Center, potential insomnia triggers present themselves throughout a patient’s cancer journey and beyond.

“Some patients, even prior to their cancer diagnosis, have chronic insomnia. Then, diagnosis itself can be very stressful, and anxiety and fear of recurrence can make it difficult to fall asleep and cause patients to wake up in the night,” Mao told Healio. “Treatment for cancer can cause pain, and steroids for symptom management can disrupt sleep acutely. When not managed appropriately, this can lead to chronic insomnia that can last for years. Last, but not least, some hormonal side effects — for example, in people with breast cancer — can cause hot flashes, which can cause patients to wake up multiple times during the night. Over time, such sleep disturbance can result in insomnia.”

Creating additional risk

Persistent insomnia can further compromise a survivor’s physical and mental health, according to Sonia Ancoli-Israel, PhD, professor emeritus of psychiatry at University of California San Diego School of Medicine. Ancoli-Israel discussed research in which she and her colleagues identified a correlation between chemotherapy and disruption of circadian rhythms. For instance, their study published in 2009 in Sleep showed that transient disruptions of the sleep-wake rhythm occur after the first administration of chemotherapy, with such disruptions becoming progressively worse with repeated chemotherapy cycles.
Such sleep impairment can have broad implications.

“We know from other studies and other types of patients that disrupted circadian rhythm increases the risk for mortality,” Ancoli-Israel told Healio. “These disrupted rhythms are also known to increase the risk for cardiovascular disease and dementia. Having poor circadian rhythms is not a good thing.”

Moreover, circadian rhythm disruption has been linked to certain cancers, making insomnia a potentially dangerous condition for survivors.

“For instance, women who do shift work have an increased incidence of breast cancer and men who do shift work have an increased incidence of prostate cancer,” Mellar P. Davis, MD, FCCP, FAAHPM, director of palliative care at Geisinger Medical Center, told Healio. “It now appears that it occurs with colorectal cancer and lung cancer as well. So, circadian rhythms are important as far as cancer prevention. People with robust circadian rhythms survive longer than those who lose their circadian rhythms.”

Certain techniques are available to cancer survivors to combat insomnia and reduce these risks. Click here to read Healio’s companion story on potential treatments of insomnia.

For more information:

Sonia Ancoli-Israel, PhD, can be reached at

Mellar P. Davis, MD, FCCP, FAAHPM, can be reached at

Jun J. Mao, MD, MSCE, can be reached at

Eric Zhou, PhD, can be reached at