Women who don’t get enough sleep may be putting their bones at risk, a new study found.

The research showed that postmenopausal women who slept less than five hours a night were 22% more likely than those who slept at least seven hours to have low bone mass and 63% more likely to have osteoporosis of the hip. Results for the spine were similar.

Bone mass is important because weaker bones are more likely to break. In the elderly, fractures can reduce quality and length of life.

In the study, which was published in the Journal of Bone and Mineral Research, researchers described the relationship between short sleep and bone health as “modest” and said it was equivalent to a year of aging.

Still, sleep, unlike many treatments, comes with no harmful side effects. “It’s not a pill. No one has to pay for it,” said Heather Ochs-Balcom, a University at Buffalo epidemiologist who led the study. “It’s just a nice easy recommendation to improve health.”

The study adds to mounting evidence that sleep has wide-ranging effects on our health. Short sleeping has been associated with cardiovascular, mood, metabolic and immune system problems.

Previous work by this team found an association between sleeping too much or too little or having disturbed sleep and recurrent falls and fractures.

This new study analyzed data on 11,084 postmenopausal women. It relied on self reports of sleep. The researchers, who were from 12 institutions, including the University of Pittsburgh, controlled for weight, smoking, age, education and several other factors. Ten% of the women said they slept less than five hours a night.

Ochs-Balcom said this study was not meant to examine why sleep affects bone health. Previous work has shown a connection between short sleep and hormonal and metabolic changes as well as inflammation.

The Philadelphia Inquirer