Amanda Phipps, PhD
Results of a new study show that women who typically slept less than the recommended 7 hours per night and were frequent snorers in the years before their cancer diagnosis experienced a poorer prognosis.
The research, published in the Journal of Sleep Medicine, involved 21,230 postmenopausal women diagnosed with a first primary invasive cancer as part of follow-up from the Women’s Health Initiative (WHI) longitudinal study. The women provided information on several sleep attributes at study baseline, including sleep duration, snoring, and components of the WHI Insomnia Rating Scale. Analyses were adjusted for potential confounding factors, such as age, cancer site, marital status, household income, smoking, physical activity, and time lag between baseline data collection and cancer diagnosis.
No significant association was observed between prediagnostic sleep characteristics taken individually and cancer survival across all tumor types combined. However, women who slept ≤6 hours per night, when combined with snoring ≥5 nights per week, did experience significantly worse cancer survival compared with those who had 7-8 hours of sleep per night and didn’t snore. Short sleep duration and frequent snoring were associated with worse breast cancer survival, and "substantially poorer breast cancer survival than those reporting neither," the authors wrote.
"We were surprised to see that snoring, especially in combination with short sleep duration, had such a strong association with cancer survival for certain cancer types," said lead author Amanda Phipps, PhD, assistant professor in epidemiology at the University of Washington. "To our knowledge, snoring has not previously been evaluated in relation to cancer survival, but our results suggest that it could be an important consideration."
According to the authors, epidemiologic studies of the relationship between sleep and cancer survival in humans have been limited. However, mouse models have demonstrated that chronic sleep problems may contribute to accelerated tumor growth and shortened cancer survival. One potential mechanism underlying this relationship is the adverse effect of poor sleep on inflammatory pathways, which may be a contributing factor in the development and progression of cancer.
"These findings reinforce our growing understanding that sleep has an effect on a broad range of health outcomes," said Phipps. "Unlike so many things that can impact cancer risk and cancer prognosis, sleep is something that an individual can potentially control. Our results provide yet another reason to make quality sleep a priority."
Phipps AI, Bhatti P, Neuhouser ML, et al. Pre-diagnostic sleep duration and sleep quality in relation to subsequent cancer survival. J Clin Sleep Med. 2016;12(4):495-503.