Kim SY, Lee MH, Lim WJ, et al. - This study draws on data from the Korean National Health and Nutrition Examination Survey to determine if vitamin D deficiency and arthritis increase the risk of short sleep duration. The sample consisted of 46,405 Korean adults. Using a self-reported questionnaire, sleep duration and arthritis history were evaluated. The duration of sleep was rated as optimal (7 to < 9 hours/day), short (< 7 hours/day), and long (≥ 9 hours/day). The levels of vitamin D were grouped as vitamin D sufficiency (≥ 20 ng/mL), insufficiency (10– 19.99 ng/mL), and deficiency (< 10 ng/mL). An increased risk of short sleep duration was associated with low vitamin D levels and the presence of arthritis. In addition, there was a positive interaction impact between vitamin D deficiency and arthritis on short sleep duration.