A recent study reported in the journal Sleep concluded that sleep efficiency, a ratio of time asleep to time spent in bed can predict survival time for women with advanced breast cancer. Results showed that higher sleep efficiency was significantly associated with lower mortality over the next six years even after adjusting for baseline prognosis factors such as age, estrogen receptor status, and treatment received. The mean survival was 68.9 months for efficient sleepers compared to 33.2 months for those with poor sleep efficiency. In addition, a 10% increase in sleep efficiency reduced the estimated hazard of subsequent mortality by 32 percent. There was no association between sleep duration and survival.
The study included 97 women with breast cancer who had a mean age of 55 years and objective sleep parameters were measured by wrist actigraphy for three consecutive nights . Overall subjects spent about 8 hours in bed but sleep for only about 6.5 hours. Authors said that although the mechanism of the relationship between sleep quality and advanced breast cancer survival is unknown , they suspect that sleep disruptions may lead to diminished immune function or impaired hormonal stress, responses that are more directly responsible for the decreased survival. More research is needed to develop and test intervent0ons adapted to cancer patients and survivors.