Women who didn't get enough sleep and snored frequently before being diagnosed with breast cancer had significantly poorer survival rates, according to a new study led by Amanda Phipps, assistant professor of epidemiology at the University of Washington School of Public Health.

"Our results suggest that sleep duration is important for breast cancer survival, particularly in women who snore," said Phipps, also an assistant member of the Public Health Sciences Division at the Fred Hutchinson Cancer Research Center. She presented the findings last month in Seattle at the annual meeting of the Associated Professional Sleep Societies. The abstract was published in the online journal Sleep.

Phipps and colleagues examined data from more than 18,000 cancer patients followed through the Women's Health Initiative, a long-term national health study that has focused on strategies for preventing heart disease, breast and colorectal cancer, and bone fractures in postmenopausal women. Participants provided information on sleep duration, snoring, and insomnia.

Researchers found that women with breast cancer who were frequent snorers and reported less than six hours of sleep were more than twice as likely to die as women with breast cancer who slept the recommended seven to eight hours a night. A similar association was noted in women with lung cancer, but it wasn't as strong, the researchers reported.

Nathaniel Watson, a professor of neurology at the University of Washington and president of the American Academy of Sleep Medicine, was senior author. Parveen Bhatti, research associate professor of epidemiology, was a co-author.