Breast Cancer Chemotherapy Impairs Sleep-wake Rhythm in Women
The September issue of Sleep journal presents a study regarding the fact that chemotherapy affects the sleep-wake rhythm of women suffering from breast cancer. The first period of chemotherapy treatment impairs the sleep-wake cadence, whereas repetitive therapy with chemo worsens the rhythm and produced more disorders.
The first week of the first period of chemo treatment showed that patients were less active during a day than in the case of healthy people. The breast cancer sufferers started their day with a delay of 30 minutes than they normally did and seized their daily activity 50 minutes earlier than their normal habit. Thus, their days were shorter during the chemotherapy. Getting to the fourth cycle of chemo treatment, the first week of this stage showed that patients increased the delay in their activity by 37 minutes, summing up 37 minutes. Things also changed with regards to the hours the women went to sleep, doing this with about 37 minutes earlier than their normal habits. Even if things went near a normal state in the second and third weeks of the first period of chemo treatment, the sleep circadian rhythm was impaired in the second and third weeks of the fourth cycle of chemo treatment.
Professor of psychiatry Sonia Ancoli-Israel from the University of California San Diego is the main researcher concerning this study. She stated that the facts presented about were not so shocking and were information of common sense. Cancer suffering patients present sleeping disorders, 30 percent up to 50 percent of them stating that they suffer from insomnia. Prior research showed that fatigue and sleeping disorders were triggered by the chemo treatments so it was logical that sleep-wake rhythm would be impaired by chemotherapy. Ancoli-Israel explains: “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.”
The research of Professor Ancoli-Israel comprised clinical trials on 95 cancer suffering women with ages averaging 50.72 years. The patients would be treated with neoadjuvant or adjuvant anthracycline-based chemo for the I-III stages of breast cancer. The women had to wear an acti-graph on their wrist for the whole period of three days prior to starting the chemo treatments. After starting the therapy against breast cancer, the patients also had to wear the acti-graph for 72 consecutive hours in first three weeks of cycle one and cycle four of the chemo treatments. Moreover, they had to keep a sleep journal in which to write the hours they went to sleep, their wake up time in the morning and sleeping periods. Then the sleep circadian figures were calculated based on the data extracted from each patient`s acti-graph. In order to vary the elements of the patients` sample, 75% of the women were Caucasian, 69 of them had a husband, 77% had studied in a college and 73% of the patients had an yearly income above $30,000.
The acrophase is an element of the circadian rhythm that shows the highest point in the sleep-awake curve in which the human is at his or her maximum activity. Compared with the figures recorded by the acti-graph during the pre-treatment period, the acrophase variable remained unchanged. All the other variables were disrupted during the first week of the first and fourth period of chemotherapy. The sleep-awake elements studied during this research were the amplitude, the mesor which is the mean of the circadian rhythm, up-mesor which represents the time of the day when the patients become more active and the down-mesor which symbolizes the period of the day in which the women became less active. Even though much information came to light thanks to this study, scientists know that much more research needs to be done for a better understanding the ways by which chemo treatments impair the sleep-wake circadian rhythm. Scientists need to take a look at psychological agents such as anxiety or depression, behavioral factors, physiological and physical agents like decreased level of feminine hormone, inflammations and so on and so forth.
The researchers believe that it is necessary to monitor the sleep-wake circadian rhythm disorders in the case of women suffering from breast cancer and undergoing chemotherapy. Moreover, it is also important to give support to the patients and offer them various types of alternative therapies along the chemo one like, for example, cognitive behavioral therapy. This should be done in order to make sure that sleep impairments do not become chronic.
