Along with a string of other health benefits, better sleep also lowers mortality among women with advanced breast cancer, according to a new study.
Sleep efficiency is defined as the ratio between time asleep and time spent in bed. Researchers from the American Academy of Sleep Medicine found that higher sleep efficiency was linked to lower mortality among women with advanced breast cancer.
The study was conducted on 97 women with an average age of 55 years, diagnosed with advanced breast cancer All participants were made to wear wrist actigraphy for three consecutive days so that researchers could keep a record of important sleep parameters. Researchers noted that although the participants spent about eight hours in bed, they slept for an average of 6.5 hours only.
Researchers also found that survival durations increased from 33.2 months for participants with poor sleep efficiency to 68.9 months for women who enjoyed better quality sleep at night. Researchers noted that a 10 percent rise in sleep efficiency resulted in a 32 percent decline in subsequent mortality rates.
"We were surprised by the magnitude of the relationship between sleep quality and overall survival even after we accounted for medical and psychological variables that typically predict survival," said lead author Oxana Palesh in a press statement. "Good sleep seems to have a strongly protective effect, even with advanced breast cancer."
This is one of the first studies to look into the association between sleep quality and survival rates among women with advanced breast cancer. However, researchers were not able to determine the exact mechanism that linked the two factors. Palesh and his team speculate that it could be because quality sleep prevents disruptions in the functions of the immunity system. Previous studies have also established that disrupted sleep impairs hormonal stress responses, which may decrease survival rates among cancer patients.
"This study emphasizes the importance of assessing sleep quality among women with breast cancer," said American Academy of Sleep Medicine President Dr. M. Safwan Badr. "Healthy sleep is critical for physical health, quality of life and overall well-being."
"There are effective treatments for sleep disruption in the general population, and some of them have shown to be effective in cancer survivors as well," said Palesh. "But much more research is needed to develop and test interventions that are adapted for cancer patients and survivors. These interventions might not only improve quality of life, but can potentially improve survival."
Breast cancer is the second most common type of cancer among woman and is also the second leading cause of death among American women, according to the American Cancer Society. One in every eight women in the country develops invasive breast cancer. According to estimates, 232,570 new cases of the disease will be diagnosed this year, resulting in 40,000 deaths.
The new study was published in the online issue of the journal Sleep and funded by National Institutes of Health, including grants from the National Cancer Institute and the National Institute on Aging.