We all have occasions when we stay up late because we’re too busy for bed…or when we toss and turn, unable to drop off or to sleep through the night. And of course, we expect to feel tired and cranky the next day.
But: Few of us, I’ll bet, would expect that going short on sleep could have serious consequences for our breasts. Yet that’s the startling conclusion of a new study linking sleep deprivation to particularly aggressive breast cancers.
Participants included 101 women with early-stage estrogen-receptor-positive breast cancer. At the start of the study, the women answered a number of health-related questions, including how long they typically slept per night during the two years before their breast cancer was diagnosed.
The women also underwent OncotypeDX testing, in which breast tumor tissue is analyzed to determine how active certain genes are. The higher the score (called a recurrence score), the more aggressive the cancer—and the more likely it is to return even after treatment. For instance, a score of less than 18 predicts a low risk for recurrence, while a score of 31 or above indicates a high risk.
Findings: Among postmenopausal women, the average recurrence score was 15 for those who routinely slept more than seven hours per night…and 19 for those who slept six to seven hours per night…but the recurrence score soared to 34 for women who usually slept only six hours or less per night. The results held even after researchers adjusted for other factors that could influence the results, such as age, body mass index, physical activity level and smoking.
Interestingly, among premenopausal women, no association was found between sleep and the risk for recurrence. However, it’s well-known that different mechanisms underlie premenopausal and postmenopausal breast cancers.
Researchers theorize that sleep may affect gene activity specifically involved in postmenopausal (but not premenopausal) breast cancer, contributing to the development of more aggressive tumors. Also, melatonin, a hormone that helps regulate sleep as well as cell growth and repair, may play a role…and people who sleep less tend to have lower melatonin levels. More research is needed to clarify the connections.
In the meantime: Prolonged periods of scanty sleep can play havoc with your health in numerous ways, including increasing the risk for heart disease, diabetes and obesity. So if you’re having trouble sleeping for at least seven hours most nights, speak to your doctor about lifestyle changes and other approaches that can help you get more rest. Your whole body—including your breasts—will be the better for it.