How well a woman with breast cancer sleeps may predict her survival, according to a small new study.
The study, published in the journal SLEEP, measured sleep efficiency, a ratio of time spent sleeping and time spent in bed, with wrist monitors in 97 women with a diagnosis of advanced breast cancer. The women with the highest sleep efficiency scores survived an average of 68.9 months, while the inefficient sleepers survived just 33.2 months.
"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," lead author Oxana Palesh, Ph.D., assistant psychiatry and behavioral sciences professor at Stanford University and research director of the Stanford Cancer Survivorship said in a statement. "Good sleep seems to have a strongly protective effect, even with advanced breast cancer."
Fewer and shorter episodes of waking up after getting into bed were also associated with longer survival. But why better sleep prolongs survival isn't totally understood, the authors write, although they suggest inefficient or disrupted sleep may impair immune system function. They advise further research examine whether treating these sleep problems could lengthen lifespans.
Consistent short sleepers are at a higher risk of dying of any cause than people who get sufficient sleep each night, according to a 2010 study. And a 2012 study found that regularly getting too little sleep may also increase a woman's risk of developing aggressive breast cancer.