Abstract P111: Sleep duration is associated with serum osteocalcin level in an elderly Korean population: the Korean Urban and Rural Elderly (KURE) study

Importance: Association between sleep duration and health related outcome studies have been published consistently. However there have been few studies of the association between sleep duration and bone formation in elderly. Objective: The aim of this study is to examine association between sleep duration and serum osteocalcin level in an elderly Korean population. Design: Cross sectional analysis using baseline cohort data. Setting: Community based setting Participants: Among the total of 927 participants, we excluded 1 participant because of the absence on sleep duration answer. A final total of 926 participants (624 women and 302 men aged 64-87 years) who completed baseline health examination in 2012 were enrolled in this study. Measurement: Sleep duration was measured by interviewer-assisted questionnaire. Participants answered their regular time of going to bed, time of opening eyes in the morning, and time of regular nap using open questions during the passing year. Serum osteocalcin level, a known biomarker of osteogenesis, was measured by electrochemiluminescence immunoassay method in the central research laboratory. The association between sleep duration (minutes/day) and serum osteoclacin level (ng/ml) was assessed by multiple linear regression analysis. Results: In the total population, sleep duration had significant association with serum osteocalcin level (ß=-0.008, p=0.013). One hour increase in sleep duration was associated with 0.48 ng/ml increase in serum osteocalcin level. This association remained after controlling for age, sex, body mass index, cigarette smoking, alcohol drinking, physical activity, and serum 25(OH) vitamin D (ß=0.012, p<0.001). This association was consistent before and after adjusting confounders in women (ß=-0.010, p=0.019, ß=-0.011, p=0.009, respectively) and men (ß=-0.013, p=0.012, ß=-0.013, p=0.011, respectively). Conclusions: Our findings suggest that longer sleep duration is associated with higher bone formation process in an elderly of Korean.