Research in post-menopausal women has found that those 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, Nork York, led the study of 11,084 post-menopausal women, all of whom were participants in the Women‘s Health Initiative.
The investigation follows an earlier one in which the team had linked short sleep to a higher likelihood of bone fracture in women. “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 Dr Heather M Ochs-Balcom, 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 re-modeling, removes old bone tissue and replaces it with new bone tissue. “If you are sleeping less, one possible explanation is that bone re-modeling 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.
The most common sites of fracture in people with osteoporosis are the hips, wrists, and spine. Spinal fractures can be serious, resulting in severe back pain, structural irregularities, and loss of height. Hip fractures are also of concern, as they often require surgery and can lead to loss of independence. They also carry a raised risk of death. 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 researchers note that the lower BMD measures among the short sleep group were equivalent to being 1 year older.
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 emphasise that there is a positive message in these findings: Sleep, as with diet and exercise, is often something that people can work to change. “It’s really important to eat health(fully), and physical activity is important for bone health. 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.”
Short sleep duration, recognized as a public health epidemic, is associated with adverse health conditions, yet little is known about the association between sleep and bone health. We tested the associations of usual sleep behavior and bone mineral density (BMD) and osteoporosis. In a sample of 11,084 postmenopausal women from the Women’s Health Initiative (WHI; mean age 63.3 years, SD = 7.4), we performed a cross‐sectional study of the association of self‐reported usual hours of sleep and sleep quality (WHI Insomnia Rating Score) with whole body, total hip, femoral neck, and spine BMD using linear regression models. We also studied the association of sleep duration and quality with dual‐energy X‐ray absorptiometry (DXA)‐defined low bone mass (T‐score < −2.5 to <−1) and osteoporosis (T‐score ≤ −2.5) using multinomial regression models. We adjusted for age, DXA machine, race, menopausal symptoms, education, smoking, physical activity, body mass index, alcohol use, physical function, and sleep medication use. In adjusted linear regression models, women who reported sleeping 5 hours or less per night had on average 0.012 to 0.018 g/cm2 significantly lower BMD at all four sites compared with women who reported sleeping 7 hours per night (reference). In adjusted multinomial models, women reporting 5 hours or less per night had higher odds of low bone mass and osteoporosis of the hip (odds ratio [OR] = 1.22; 95% confidence interval [CI] 1.03–1.45, and 1.63; 1.15–2.31, respectively). We observed a similar pattern for spine BMD, where women with 5 hours or less per night had higher odds of osteoporosis (adjusted OR = 1.28; 95% CI 1.02–1.60). Associations of sleep quality and DXA BMD failed to reach statistical significance. Short sleep duration was associated with lower BMD and higher risk of osteoporosis. Longitudinal studies are needed to confirm the cross‐sectional effects of sleep duration on bone health and explore associated mechanisms. © 2019 American Society for Bone and Mineral Research.
Heather M Ochs‐Balcom, Kathleen M Hovey, Christopher Andrews, Jane A Cauley, Lauren Hale, Wenjun Li, Jennifer W Bea, Gloria E Sarto, Marcia L Stefanick, Katie L Stone Nelson, B Watts, Oleg Zaslavsky, Jean Wactawski‐Wende