Many women diagnosed with breast cancer have problems sleeping during treatment. The study reviewed here found that changes in heart rate and cortisol (a steroid produced by the body) levels were linked to sleep problems in women being treated for advanced (metastatic) breast cancer.
Many things can cause sleeping problems during breast cancer diagnosis and treatment:
and can make it hard to fall asleep, stay asleep, or get quality sleep. In this small study, the researchers wanted to know if any bodily changes were happening along with the sleeping problems.
The researchers monitored the sleep quality of 99 women being treated for advanced (metastatic) breast cancer:
The researchers evaluated the women's psychological well-being and stress levels using psychological tests. They also monitored the women's breathing and heart rate patterns while they were asleep, as well as saliva levels of cortisol, a naturally occurring stress hormone.
It's not clear whether the heart rate and cortisol level changes cause the sleep problems or if they're the result of the sleep problems. These heart rate and cortisol level changes also could be a side effect of breast cancer or treatment. Still, this study may give doctors some ideas on how to better address sleep problems that happen during treatment for breast cancer and other diseases.
If you're having troublesome sleep problems during breast cancer treatment, talk to your doctor about how you can improve the quality of your sleep. You also might want to consider a complementary and holistic medicine technique to improve your sleep. Complementary and holistic medicine techniques seek to address how disease and side effects affect your whole person: physically, emotionally, spiritually, and socially. Techniques such as yoga, hypnosis, guided imagery, meditation, and progressive muscle relaxation can improve breathing and heart rate patterns, help relieve stress, and promote better sleep. Visit the Breastcancer.org Complementary and Holistic Medicine section to learn about these and other techniques.
ROCHESTER, N.Y., Oct. 15 (MedPage Today) -- Sleep disruptions in women with advanced breast cancer are accompanied by alterations in heart rhythm and cortisol release patterns, researchers here said.
Respiratory sinus arrhythmia -- the normal increase in heart rate during inspiration relative to expiration -- was significantly diminished in women with metastatic breast cancer who had trouble sleeping, reported Oxana Palesh, Ph.D., of the University of Rochester, and colleagues in the Oct. 15 issue of the Journal of Clinical Sleep Medicine.
Baseline respiratory sinus arrhythmia scores were correlated positively with sleep efficiency (r=0.39, P=0.001) and negatively with wakefulness after sleep onset (r=-0.38, P=0.002), the researchers found.
Low degrees of respiratory sinus arrhythmia were also associated with longer nocturnal wake episodes and reduced sleep duration as reported by patients.
Additionally, morning-to-evening decreases in cortisol release were smaller than normal. Flatter cortisol slopes predicted longer periods of nocturnal wakefulness (r=0.21, P=0.04), the researchers said.
In sum, the findings suggested that autonomic and hormonal functioning was disrupted in parallel with sleep abnormalities in these patients.
But, the researchers said, the cross-sectional study design did not permit them to assign causality.
On the other hand, they pointed out, the findings could not be explained by the stress of having metastatic cancer. Measures of psychological stress and disease severity were not significantly associated with most of the sleep disruption parameters analyzed in the study.
The researchers said that the study provides "further clues to why poor sleep is bad for health."
"Interventions aimed at correcting autonomic functioning and hormone disruptions might prove valuable in treating insomnia in women with cancer," they added.
Earlier research had shown that sleep disruption is up to three times as common among cancer patients than in the general population.
Abnormalities in respiratory sinus arrhythmia had been found previously in people with non-cancerous medical and psychiatric conditions, including depression. But the interrelation of these heart rhythm disturbances and sleep in cancer patients had not been studied before.
So Dr. Palesh and colleagues recruited 99 women with breast cancer to undergo nocturnal actigraphy as well as daytime measurements of respiratory sinus arrhythmia, saliva cortisol levels, and various aspects of psychosocial health.
The latter were assessed with the Trier Social Stress Test, the Perceived Stress Scale, the Beck Depression Inventory, the DSM-IV Structured Clinical Interview, and a pain rating scale.
With few exceptions, correlation coefficients between scores on these measures and sleep disruption parameters did not reach 0.15 (positive or negative) or achieve statistical significance.
There was a modest association between Perceived Stress Scale scores and sleep latency (r=0.22, P<0.05).
Also, pain intensity and a composite of antidepressant use and DSM-IV interview scores correlated significantly with time in bed, although not with sleep duration or interruptions.
Most measures of disease severity failed to correlate with sleep abnormalities.
But respiratory sinus arrhythmia, at baseline and as area under the curve over a 50-minute period during stress testing, did correlate significantly with sleep disruption.
Baseline arrhythmia scores showed significant correlations in three of six parameters.
The area under the curve significantly predicted five of six parameters with r values ranging from 0.26 (mean duration of wake episodes) to 0.45 (total duration of wakefulness after sleep onset).
The researchers said it was unlikely that the results stemmed from the physical effects of metastatic breast cancer or its treatment, because similar findings have been seen in other populations.
They said it was possible that disruption of sleep itself could affect respiratory sinus arrhythmia and cortisol release.
They also pointed out that their study design did not include cortisol measurements at night. Cortisol rhythms in their sample might have shifted relative to patients' sleep cycles, "which would give the appearance of a flattened daytime slope."
Dr. Palesh and colleagues said a longitudinal study that included 24-hour cortisol measurements would clear up some of these ambiguities.
Interventions aimed at normalizing autonomic and hormonal function need not be pharmacologic, Dr. Palesh said.
Basic stress-management techniques aimed at inducing diaphragmatic breathing can be helpful, she said. These may include yoga, biofeedback therapy, hypnosis, visualization exercises, meditation, or progressive muscle relaxation.
The study was funded by the National Institute on Aging, the National Cancer Institute, and the National Center for Research Resources.
No potential conflicts of interest were reported.
Primary source: Journal of Clinical Sleep Medicine Source reference: Palesh O, et al "Vagal regulation, cortisol and sleep disruption in women with metastatic breast cancer" J Clin Sleep Med 2008; 5: 441-49.
Breastcancer.org is a non-profit organization dedicated to providing information and community to those touched by this disease. Learn more about our commitment to providing complete, accurate, and private breast cancer information.
Breastcancer.org 7 East Lancaster Avenue, 3rd Floor Ardmore, PA 19003
©2011 Breastcancer.org - All rights reserved.
