BUFFALO, N.Y. — Getting five or fewer hours of sleep a night is associated with low bone mineral density (BMD) and higher odds of osteoporosis, according to the findings of the largest study of sleep and BMD to date among U.S. postmenopausal women.

“Our study suggests that sleep may negatively impact bone health, adding to the list of the negative health impacts of poor sleep,” said study lead author Heather Ochs-Balcom, PhD, associate professor of epidemiology and environmental health at the University at Buffalo School of Public Health and Health Professions.

“I hope that it can also serve as a reminder to strive for the recommended seven or more hours of sleep per night for our physical and mental health,” Ochs-Balcom added.

The study, published earlier this month in the Journal of Bone and Mineral Research, focused on 11,084 postmenopausal women from the Women’s Health Initiative. Women who self-reported sleeping five hours or less per night had significantly lower bone mineral density at four sites — whole body, hip, neck and spine — compared to women who slept seven hours a night. The difference they observed is equivalent to one year of aging.

Researchers note there was no statistical difference among women who slept more than seven hours.

The body undergoes an array of healthy processes during sleep, including bone remodeling, during which old tissue is removed and new bone tissue is formed. “There’s a rhythm throughout the day. If you are sleeping less, one possible explanation is that bone remodeling isn’t happening properly,” Ochs-Balcom said.

The current study is a follow-up to research the team published last year that found that women who had short sleep were more likely to sustain a fracture.

“The question was, is it because they’re up and walking around more, or because they really have lower bone mineral density?” Ochs-Balcom said. “I said why don’t we take a look at it because we have a sample of BMD scans from 11,000 women. This helps tell more of the story.”

While the findings might be the stuff of nightmares for older adults, the silver lining is that sleep is something people can control, along with adding in a few extra healthy behaviors.

Poor sleep is linked to a number of adverse health conditions, including obesity, diabetes, hypertension and cardiovascular disease.

“It’s really important to eat healthy, and physical activity is important for bone health,” Ochs-Balcom said. “That’s the exciting part of this story — most of us have control over when we turn off the lights, when we put the phone down.”

UB School of Public Health and Health Professions Dean Jean Wactawski-Wende and Kathleen Hovey, data manager/statistician for the school’s Department of Epidemiology and Environmental Health, contributed to the paper.

Other co-authors include researchers from the University of Michigan; University of Pittsburgh; Stony Brook University; University of Massachusetts Medical School; University of Arizona Cancer Center; University of Wisconsin-Madison; Stanford University; California Pacific Medical Center; University of California, San Francisco; University of Washington; and Mercy Health Osteoporosis and Bone Health Services, Cincinnati.