Study Hints BMD Is Linked to How Long It Takes to Fall Asleep

A study says it found a link between bone mineral density and sleep onset latency in an elderly population.

Previous clinical investigations involving the associations between sleep disorders and osteoporosis have produced inconsistent results. A recent study found evidence of a significant link between bone mineral density (BMD) and sleep onset latency, suggesting that BMD measurements and interventions for osteoporosis may be valuable for elderly patients with sleep problems.

The researchers of the study analyzed 410 patients who attended the Zhejiang Hospital for a sleep evaluation. The study used dual-energy X-ray absorptiometry to measure BMD and T-score at femoral neck and lumbar spines over L2-L4 regions, while sleep status was evaluated using the Pittsburgh Sleep Quality Index (PSQI). The PSQI considered 7 components, such as sleep quality, sleep disturbances, sleep duration, and use of sleep medication.

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“More interestingly, a research study demonstrated that sleep deprivation could increase cortisol concentration, which might decrease bone formation and bone mineral density (BMD). In addition, a large number of studies have demonstrated that short sleep or long sleep resulted in elevated pro-inflammatory cytokines, including C-reactive protein, and interleukin-6, which subsequently increased osteoclast activity and consequent bone loss. Thus, it is reasonable to speculate that insomnia is related to OP,” the authors stated.Most of the study participants with osteoporosis (OP) were female and had lower body mass indexes (BMI), as well as higher sleep onset latency scores. The Spearman correlation test, which was conducted to find the relationship between BMD and other factors, revealed that gender, BMI, score of total PSQI, and sleep onset latency were significantly related to BMD and T-score in femoral neck and lumbar region L2-L4.

Furthermore, the researchers performed a multinomial logistic regression analysis, which demonstrated that gender and age were independent factors for OP and osteopenia. When they adjusted the analysis for gender, age, and BMI, sleep onset latency of less than 15 minutes and of 16-30 minutes were found to be less likely to have reduced BMD.

“So far, previous research concerning the relationship between sleep duration and BMD obtained conflicting results, with some reporting the independent risk of short sleep for OP and others showing an independent risk in long sleepers,” explained the authors. “Our present work, to our knowledge, was the first to find that long sleep onset latency was an independent risk for reduced BMD

The researchers concluded that their results demonstrate that sleep onset latency may be related to reduced BMD in elderly patients with insomnia. These results emphasize the importance of screening and intervening for OP in elderly patients with sleep problems. Additionally, the authors noted the need for further research involving the possible mechanisms by which long sleep onset latency could contribute to reduce BMD.

Reference

Tong Q, Wu W, Wu Q, et al. Sleep onset latency is related with reduced bone mineral density in elderly people with insomnia: a retrospective study. [published online August 30, 2018]. Clin Interv Aging. doi: 10.2147/CIA.S161922.