Vitamin D supplement intake and its association with sleep quality among medical students

Background: Vitamin D deficiency is highly prevalent in Saudi Arabia and is considered a significant public health issue. Emerging evidence suggests a potential link between Vitamin D levels and sleep quality. This study aimed to investigate the association between Vitamin D supplement intake and sleep quality among medical students at King Abdulaziz University (KAU), Jeddah, Saudi Arabia. Subjects and Methods: A cross-sectional study was conducted at the Faculty of Medicine, KAU, from September 2020 to April 2022. Data were collected via a self-administered electronic survey completed by medical students who consented to participate. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Statistical analyses, including the Chi-squared test and the Mann–Whitney U -test, were employed to evaluate associations between Vitamin D supplementation and sleep quality. Results: A total of 222 students participated in the study, with a mean age of 22.1 ± 1.6 years; 75.7% of students were female. The mean PSQI score was 6.81 ± 3.45, with 58.6% of participants having poor sleep quality. While 31.3% of students reported using Vitamin D supplements, only 17.8% of students were aware of their Vitamin D levels. The median with interquartile range of serum 25(OH) Vitamin D level was 26.5 (18.3–52.5) nmol/L. No significant association was found between sleep quality and Vitamin D supplement intake ( P = 0.377). Participants with poor sleep quality had slightly lower median of 25(OH) Vitamin D levels (25.5 [19.8–50.8] nmol/L) compared to those with good sleep quality (27.0 [17.8–61.0] nmol/L), but this difference was not statistically significant ( P = 0.955). Conclusion: This study found no significant association between sleep quality and Vitamin D supplement intake among medical students. Given the study’s cross-sectional nature and limited sample size, larger prospective studies are needed to validate these findings.