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