AASM logo text

Chemotherapy it appears could wreak havoc on the sleep patterns of women with breast cancer. The outcome of a new study claimed that the sleep-wake activity rhythms of breast cancer patients may get damaged during the administration of chemotherapy. Results point out that the first cycle of chemotherapy is apparently linked with a brief disturbance of these rhythms, while frequent administration of chemotherapy may lead to increasingly worse and more lasting impairments.

Experts reveal that during the first week, in the first cycle of chemotherapy, subjects supposedly changed from low to high activity about 30 minutes later in the day. They reduced their level of activity about 50 minutes earlier at night, signifying that their days may be shorter. In the first week of the fourth cycle of chemotherapy, the women apparently raised their level of activity about 37 minutes later in the day and supposedly changed from high to low activity about 34 minutes earlier at night.

Even though nearly all variables came back to baseline levels in the second and third weeks of the first cycle of chemotherapy, circadian impairments may be retained on numerous variables in the second and third weeks of cycle four.

Principal investigator, Sonia Ancoli-Israel, PhD, professor of psychiatry at the University of California San Diego, mentioned, that the findings were not shocking at all. Sleep disturbances may be familiar with cancer patients, with an approximate 30 percent to 50 percent accounting for symptoms of insomnia. Preceding studies have also illustrated that both sleep and fatigue may get worse with chemotherapy, so it was anticipated that circadian rhythms may go down.

Ancoli-Israel, commented, “Results of this study suggest that our biological clocks are affected by chemotherapy. Our biological clock, or circadian rhythm (24-hour cycles), help keep our bodies in sync with the environment. During chemotherapy, our biological clock gets out of sync, especially after the first cycle of treatment. The clock seems to regulate itself after only one cycle, but with repeated administration of chemotherapy, it becomes more difficult for the biological clock to readjust.”

Approximately 95 women with ages from 50 to 72 years were apparently planned to receive neoadjuvant or adjuvant anthracycline-based chemotherapy for stage I-III breast cancer. The subjects supposedly wore a wrist actigraph for 72 successive hours at baseline i.e. pre-chemotherapy, as well as throughout the first, second and third weeks of both cycle one and cycle four of chemotherapy.

At every assessment they also apparently finished a sleep log to document their bedtime, wake time and napping periods. Sleep-wake circadian activity variables could be calculated based on actigraphic data. From the participants, about 75 percent were Caucasian. Married people constituted to roughly 69 percent. Some college education was seen in about 77 percent. An annual income of $30,000 was supposedly seen in an approximate 73 percent of the subjects.

As opposed to baseline measures, all circadian rhythm variables except acrophase which is claimed to be the time of day of the peak of the curve were drastically damaged throughout the first week of both the first and fourth chemotherapy cycles. These circadian rhythm variables may incorporate amplitude i.e. the height of the circadian rhythm and mesor which is the mean of the rhythm. It was also found to include up-mesor i.e. the time of day when activity was switched from low to high, and down-mesor which is the time of day when activity switched from high to low.

As per the study, additional investigation may need to be conducted in order to better comprehend the mechanisms through which chemotherapy may add to impairments in sleep-wake activity. Prospective mechanisms may comprise of psychological factors i.e. anxiety and depression and behavioral factors like increased daytime napping, as well as physiological factors and physical symptoms, such as reduced levels of estrogen, impaired cortisol responses and inflammation.

The authors mentioned that it may be imperative to monitor more regularly for sleep and circadian disruptions in breast cancer patients experiencing chemotherapy. They explain that it is also important to present suitable management like cognitive behavioral therapy or bright light therapy, in order to put off sleep disturbances from becoming persistent in such patients.

This study was published in the journal Sleep.