Short sleep may worsen bone health for women
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Postmenopausal women who report sleeping less than 5 hours per night are more likely to develop low bone mineral density at all major sites and are at increased risk for osteoporosis at the hip and spine, according to findings published in the Journal of Bone and Mineral Research.
“Sleep is associated with another health outcome, and this time it is bone health,” Heather Ochs-Balcom, PhD, associate professor in the department of epidemiology and environmental health at the University at Buffalo School of Public Health and Health Professions at the State University of New York, said in a press release. “Our work provides another, and relatively easy, reason to try and get at least 7 hours of sleep per night."
In a cross-sectional study, Ochs-Balcom and colleagues analyzed data from 11,084 postmenopausal women aged 50 to 79 years at baseline who participated in the Women’s Health Initiative and underwent DXA measurements at one of three clinical centers (mean age, 63 years; 78% white). Women underwent hip, spine and whole-body DX scans and completed sleep questionnaires at baseline. Researchers used adjusted linear regression models to examine the associations between usual sleep duration and sleep quality with site-specific BMD measures, and also used multinomial regression models to assess the association between sleep duration and quality with low bone mass, defined as a T-score between –2.5 to –1, and osteoporosis.
Within the cohort, 10% of women reported sleeping 5 hours or less per night and 4.5% reported sleeping 9 hours or more per night. Approximately 33% met the threshold for insomnia.
In adjusted linear regression models, women who reported sleeping 5 hours or less per night had on average 0.012 g/cm2 to 0.018 g/cm2 lower BMD at all four sites compared with women who reported sleeping 7 hours per night. Spine and whole-body BMD values were also on average 0.01 g/cm2 lower for women who reported sleeping 6 hours per night when compared with women who slept 7 hours per night.
In the adjusted multinomial models, women who reported sleeping 5 hours or less per night were more likely to have low bone mass (OR = 1.22; 95% CI, 1.03-1.45) and osteoporosis of the hip (HR = 1.63; 95% CI, 1.15-2.31) compared with women who slept 7 hours per night. Researchers also observed a similar pattern for spine BMD, noting women who slept less than 5 hours per night had higher odds for osteoporosis (adjusted OR = 1.28; 95% CI 1.02-1.6) compared with women who slept 7 hours per night.
Associations between sleep quality and BMD did not reach statistical significance, according to the researchers.
“We found that women who reported sleeping 5 hours or less per night had bones that were about 1 year older compared with women who reported sleeping 7 or more hours," Ochs-Balcom said."Given the fact that one in three women aged 50 years or older will experience a fracture, it is important to find new ways to improve bone health."
The researchers noted that the findings provide epidemiologic evidence of sleep as a partially modifiable risk factor for BMD that deserves further replication.
“Research suggests that bone metabolism has a circadian rhythm, which can be disrupted in a state of too little sleep," Ochs-Balcom said. "What we could do next is study whether circadian rhythm genes shown to be involved in bone mass from animal studies are also important in humans, and whether we can detect bone remodeling differences between short and normal sleepers." – by Regina Schaffer
Disclosures: One of the authors reports she has received a grant from Merck.
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