In the study conducted over women with metastatic breast cancer, the researchers found that breathing, heart rates and cortisol levels can help predict insomnia.
Lead author Oxana Palesh, Ph.D., research assistant professor at Rochester's James P. Wilmot Cancer Centre said that identifying the body's parasympathetic nervous system, a branch of the autonomic nervous system that controls breathing and heart rates and the body's response to stress, act as a contributor to poor sleep, which is a persistent problem for women with breast cancer.
"We were able to identify the role that the parasympathetic nervous system plays in insomnia. It's reasonable to suggest that simple breathing exercises may help more than we realize with insomnia," said Palesh.
She suggested that regulating deep diaphragmatic breathing through yoga, meditation and other techniques might help in preventing insomnia and sleep disruptions in cancer patients.
During the study, out of 99 women with metastatic breast cancer or recurrent disease over 45, 39 took antidepressants and 19 used medications to treat their insomnia.
The scientists measured participants' heart rate during a stress task and found that lowered heart rate variability was associated with efficiency of their sleep.
They found that most women spent about eight hours in bed at night, but had on average 15 wake episodes in the night with each episode lasting about 5 minutes, for a total of 71 minutes
Insomnia can reduce quality of life for people facing the disease.
The research showed that more than a third of the women with metastatic breast cancer, circadian rhythms are disrupted and cortisol peak multiple times or rise during the end of the day.
The study is published in the Journal of Clinical Sleep Medicine.