Association between self-reported sleep duration and serum vitamin D level in elderly Korean adults.

ObjectivesTo investigate the association between self-reported sleep duration and serum vitamin D level in elderly Korean adults. DesignCross-sectional data analysis. SettingKorean National Health and Nutrition Examination Survey 2010. ParticipantsNoninstitutionalized adults aged 60 to 80 (N=1,614). MeasurementsThe confounding variables were serum 25-hydroxy vitamin D level, age, sex, body mass index, smoking history, alcohol consumption, and self-reported daily sun exposure and sleep duration. Self-reported daily sleep duration was divided into four groups: Q1 (4hours), Q2 (5-6hours), Q3 (7-8hours), and Q4 (9hours). ResultsMean serum vitamin D levels of subjects in the Q1, Q2, Q3, and Q4 groups were 44.18, 48.08, 48.83, and 51.78nmol/L, respectively. On multivariate linear regression analysis, subjects in the Q2 (B=3.80, 95% confidence interval (CI)=0.42-7.19), Q3 (B=4.89, 95% CI=1.54-8.24), and Q4 (B=5.18, 95% CI=0.78-9.58) groups had significantly higher serum vitamin D levels than subjects in the Q1 group. ConclusionSerum vitamin D level is positively associated with self-reported daily sleep duration in elderly Korean individuals. These results suggest that inadequate sleep duration may be associated with lower vitamin D levels in elderly adults.