A recent randomised, double blind, clinical trial conducted by Majib et al (2017) determined the beneficial effect of vitamin D supplementation on sleep score and quality in 20-50 year-old people with known sleep disorders according to the Pittsburg Sleep Quality Index (PSQI).
The trial studied 89 subjects (44 in the intervention group and 45 in the placebo group) split into an intervention group (n=44) and control group (n=45). Subjects included were not allowed to be taking any sleep medications, were not allowed to have used vitamin D in the three months prior to the study, and were not allowed to partake in sleep disturbing activities such as consuming alcohol and smoking. Subjects in the intervention group were given 50,000 units of vitamin D once a fortnight for eight weeks while the control group were given a placebo. Several qualitative and quantitative assessments were conducted before and after the intervention and included the Petersburg’s Sleep Quality Questionnaire, International Physical Activity Questionnaire, general information questionnaire, sun exposure, vitamin D serum level and 3-day food record questionnaire to assess participant outcomes.
At the end of the eight-week trial, PSQI scores were reduced significantly amongst vitamin recipients compared with placebos (P<0.05) and the difference was significant even after modifying confounding variables. Vitamin D supplementation was found to improve sleep quality, reduce sleep latency, increase sleep duration and improve subjective sleep quality.
- Majid MS, Ahmad HS, Bizhan H, et al. The effect of vitamin D supplement on the score and quality of sleep in 20-50 year-old people with sleep disorders compared with control group. Nutr Neurosci 2017:1-9.