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Aerobic exercise may improve sleep quality for breast cancer survivors
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A physical activity intervention significantly reduced perceived sleep dysfunction among breast cancer survivors, according to results of a randomized controlled study.
Laura Q. Rogers, MD — professor in the department of nutrition sciences at The University of Alabama at Birmingham, senior scientist in the UAB Nutrition Obesity Research Center and the Center for Exercise Medicine, and the cancer control and population science program at UAB Comprehensive Cancer Center — and colleagues assessed whether a 3-month physical activity behavior program could improve self-reported sleep outcomes among breast cancer survivors.
Results showed survivors assigned the intervention demonstrated significant improvements in Pittsburgh Sleep Quality Index (PSQI) global sleep quality at 3 months (mean between-group difference = –1.4; 95% CI, –2.1 to –0.7) and 6 months (mean between-group difference = –1; 95% CI, –1.7 to –0.2) compared with survivors who received usual care.
Survivors assigned the intervention also reported improvement at 3 months on several PSQI subscales, including sleep quality (mean between-group difference, –0.3; 95% CI, –0.4 to –0.1), sleep disturbances (mean between-group difference, –0.2; 95% CI, –0.3 to –0.03) and daytime dysfunction (mean between-group difference, –0.2; 95% CI, –0.4 to –0.02). However, those improvements did not persist at 6 months.
Question: How did this study come about?
Answer: Realizing the importance of physical activity for improving health and well-being after a breast cancer diagnosis, I sought assistance from a team of experts in the development of a program called BEAT Cancer that helps breast cancer survivors engage in more aerobic physical activity. We wanted to determine the benefits of the BEAT Cancer physical activity program before recommending broader use. We also hoped that, by demonstrating the program’s benefits, we could increase the likelihood that third-party payers would cover the cost of providing these types of programs for patients.
Q: What prompted you to study the association between aerobic activity and sleep in breast cancer patients in this way?
A: Our scientific publication focused on sleep quality because poor sleep can be a frequent and persistent problem for cancer survivors, even after completing their cancer treatment. It is estimated that more than one-third of the more than 3 million breast cancer survivors in the United States have trouble sleeping. When cancer survivors are asked what are the most important symptoms that affect their quality of life, poor sleep quality is among the top five. Further, poor sleep causes unhealthy metabolic changes and may be associated with an increased risk for death. Clearly, this is an important symptom for cancer survivors that warrants attention and management.
Q: How did you conduct the study?
A: This was a randomized controlled trial. Breast cancer survivors were randomly assigned to receive the BEAT Cancer program or written materials. The 3-month BEAT Cancer program gradually increased the recipient’s physical activity behavior to a goal of 150 weekly minutes of moderate-intensity aerobic physical activity. BEAT Cancer recipients attended 12 supervised exercise sessions tapered over the first 6 weeks to entirely unsupervised (ie, home-based) exercise during the second 6 weeks. To help BEAT Cancer participants continue the exercise on their own, they also attended six discussion group sessions to develop strategies for continuing exercise long term. Most participants did walking as their aerobic exercise. We measured sleep at baseline, at the end of the 3-month program and then at 6 months after baseline. We measured sleep using a standard self-report measure and also with a motion sensor that study participants wore on their wrists at night.
Q: What did your study show?
A: The BEAT Cancer program resulted in clinically important improvements in overall self-reported sleep quality, with statistically significant benefit continuing 3 months after program completion. These improvements were primarily due to changes in the aspects of perceived quality (very bad, fairly bad, fairly good or very good), frequency of sleep disturbances and daytime dysfunction (eg, dozing off).
Q: How might these results affect clinical practice?
A: These results add further support to the importance of aerobic physical activity for cancer survivors. We have strong evidence for using yoga to improve sleep, but now health care providers caring for breast cancer survivors also can recommend aerobic physical activity, such as walking for 150 minutes per week at a moderate intensity. Clinical practice should use this information to motivate breast cancer survivors to adopt a more physically active lifestyle. Health care systems responsible for the health of populations should consider supporting lifestyle programs with proven benefits that can improve cancer survivors’ health and well-being.
Q: Did any of these findings surprise you?
A: We were surprised by the lack of intervention effect on the sleep aspects measured by the motion sensor — such as how quickly a person falls asleep and the percentage of time in bed that a person is asleep. Another study performed by a different group of scientists had reported motion sensor-measured benefits, and we thought the different results for self-report compared with motion sensor in prior studies was due to small sample sizes. Seeing this unexpected discrepancy with a larger study demonstrates the need for more research in this area. We also were surprised by the high percentage of participants who were poor sleepers at time of study enrollment. A breast cancer survivor didn’t have to have poor sleep to join the study, yet two-thirds were poor sleepers at the time they enrolled, even though it had been 4.5 years on average since their breast cancer diagnosis.
Q: What should future research entail?
A: We are planning further studies to determine why the program effects differed for the self-report and accelerometer measures, how physical activity interacts with a person’s circadian rhythm, and what role the discussion group sessions and staff support played in our results. We also hope to determine mechanisms responsible for physical activity effects on sleep quality among breast cancer survivors and how these mechanisms can be used to optimize physical activity recommendations. I would like to see the research related to aerobic physical activity and sleep among breast cancer survivors move forward by determining the effects of physical activity on objective sleep outcomes measured with strategies beyond the accelerometer-based motion sensor alone. Also, studies are needed to determine if physical activity can work synergistically with other sleep enhancing strategies. – by Rob Volansky
Reference:
Rogers LQ, et al. Med Sci Sports Exerc. 2017;doi:10.1249/MSS.0000000000001327.
For more information:
Laura Q. Rogers, PhD, can be reached at Department of Nutrition Sciences, School of Health Professions, 1720 2nd Ave. South, Birmingham, AL 35294-3360; email: rogersl@uab.edu.
Disclosure: Rogers reports no relevant financial disclosures.