Sleep onset latency is related with reduced bone mineral density in elderly people with insomnia: a retrospective study

PURPOSE: Inconsistent outcome about association between insufficient sleep and bone mineral density (BMD) has been reported. The present study aimed to determine whether BMD was associated with score of Pittsburgh Sleep Quality Index (PSQI). METHODS: A total of 410 patients (mean age 81.6±5.9 years) attending our hospital for evaluation of sleep were retrospectively studied. Dual-Energy X-ray Absorptiometry was used to measure BMD and T-score at femoral neck and lumbar spines over L2–L4 regions. Subjective sleep status was evaluated by the PSQI questionnaires. The Mann–Whitney U test and chi-square analysis were used to compare continuous variables and categorical variables, respectively. Spearman correlation test was conducted to find the relationship between BMD and other clinical factors. Multinomial logistic regressions analysis was performed to analyze independent factors predicting BMD. RESULTS: Majority of the participants with osteoporosis (OP) were female and had lower body mass index (BMI) and higher sleep onset latency score. Spearman correlation test showed 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. Finally, multinomial logistic regression analysis demonstrated that gender and age were independent factors for OP and osteopenia and that after adjustment for gender, age, and BMI, sleep onset latency of <15 minutes (OR: 0.38; 95% CI: 0.15–0.96; P=0.04) and 16–30 minutes (OR: 0.37; 95% CI: 0.17–0.79; P=0.01) were less likely to have reduced BMD. CONCLUSION: There was a significant association between BMD and sleep onset latency, suggesting that, in elderly patients with sleep problem, BMD measurement and intervention for OP might be valuable.