At least 5 hours !

New research has revealed that those women who slept for no longer than 5 hours per night were most likely to have lower bone mineral density (BMD) and osteoporosis.

A team from the University at Buffalo, NY, led the study of 11,084 postmenopausal women, all of whom were participants in the Women’s Health Initiative.

A recent paper in the Journal of Bone and Mineral Research gives a full account of the findings.

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

“I hope,” she adds, “that it can also serve as a reminder to strive for the recommended 7 or more hours of sleep per night for our physical and mental health.”

Bone is living tissue that undergoes continuous formation and resorption. The process, known as bone remodeling, removes old bone tissue and replaces it with new bone tissue.

“If you are sleeping less, one possible explanation is that bone remodeling isn’t happening properly,” Ochs-Balcom explains.

The term osteoporosis means porous bone and refers to a condition that develops when the quality and density of bone are greatly reduced. Osteoporosis is more common in older adults, with older women having the highest risk of developing it.

In most people, bone strength and density peak when they are in their late 20s. After that, as they continue to age, the rate of bone resorption gradually overtakes that of formation. The bone density of women reduces more rapidly during the first few years after menopause.

Worldwide, around 1 in 3 women and 1 in 5 men in their 50s and older are at risk of experiencing bone fracture due to osteoporosis, according to the International Osteoporosis Foundation.

In the new study, the team found that compared with women who slept more, those who reported getting only up to 5 hours of sleep per night had significantly lower values in four measures of BMD.

The four BMD measures were of the whole body, the hip, the neck, and the spine.

The results were independent of other factors that could potentially influence them, such as age, race, the effects of menopause, smoking status, alcohol use, body mass index (BMI), use of sleeping pills, exercise, and type of bone density scanner.

The researchers emphasize that there is a positive message in these findings: Sleep, as with diet and exercise, is often something that people can work to change.