The association between vitamin D status and sleep duration in school-aged children; the CASPIAN-V study.

Background: Considering the high prevalence of both vitamin D deficiency (VDD) and sleep impairment in children and adolescents, this study was conducted to determine the association between VDD and sleep duration in the Iranian pediatric population. Methods: This multicentric national study was conducted in 2019 on 2564 frozen sera obtained from 7 to 18- year students who were studied in the fifth survey of a national school-based surveillance program conducted in 30 provinces of Iran. Sleep duration was assessed using a questionnaire based on the World Health Organization-Global School-based Student Health Survey protocol. Short sleep duration was defined as sleep duration less than 8 h/day VDD Vitamin D < 20 ng/dL, and vitamin D insufficiency as 20-30 ng/dL.An adjusted logistic regression model was applied to evaluate the associations of vitamin D status with sleep duration. Results: The Mean (SD) of students' age was 12.1(3.0) years; overall 10.6%of participants had VDD and 23% of participants had short sleep duration. in the adjusted logistic model, Conclusion: The current study showed that low Vitamin D levels (insufficient and deficient)were significantly associated with short sleep duration in school-aged children. Further studies are recommended to determine the efficacy of vitamin D replacement in improving sleep duration and quality.