Objectives: Sleep quality may be directly related with vitamin D serum level. Some studies found that
people with lower vitamin D serum level experienced a lower sleep quality. Consequently, this study aimed at determining
the effect of vitamin D supplements on sleep score and quality in 20–50 year-old people with sleep disorders.
Methods: This double blind, clinical trial was performed in November 2015–February 2016 on 89
people with sleep disorders based on Petersburg’s Sleep Index. Patient samples were divided randomly into 2 groups:
intervention and placebo. At the end of the study, the data on 89 subjects (44 in intervention group and 45 people in
placebo group) were examined. Intervention group received a 50 000-unit vitamin D supplement, one in a fortnight for 8
weeks. Meanwhile, placebo group received placebo. Before and after intervention, Petersburg’s Sleep Quality Questionnaire,
International Physical Activity Questionnaire, general information questionnaire, sun exposure, vitamin D serum level and
3-day food record questionnaire were assessed and recorded for all participants. To analyze data, t-test,
chi square, ANCOVA, U-Mann-Whitney and Wilcoxon statistical tests were used.
Findings: Based on the results of the present study, at the end of the study sleep score
(PSQI) reduced statistically-significantly in vitamin recipients as compared
with placebo recipients (p < 0.05). This difference was statistically-significant even after modifying confounding variables
(p < 0.05).
Conclusion: This study shows that the use of vitamin D supplement improves sleep quality, reduces sleep
latency, raises sleep duration and improves subjective sleep quality in people of 20–50 year-old with sleep disorder.
[Keywords: Vitamin D supplement, serum vitamin D, sleep disorders]