Background: Vitamin D exerts multiple pleiotropic effects beyond its role in calcium-phosphate metabolism.
Growing evidence suggests an association between hypovitaminosis D and sleep disorders, thus increasing
the interest in the role of this vitamin in the regulatory mechanisms of the sleep-wake cycle.
Objective: The study aimed to explore and summarize the current knowledge about the role of vitamin D in sleep
regulation and the impact of vitamin D deficiency on sleep disorders.
Methods: The main regulatory mechanisms of vitamin D on sleep are explained in this study. The literature was
scanned to identify clinical trials and correlation studies showing an association between vitamin D deficiency
and sleep disorders.
Results: Vitamin D receptors and the enzymes that control their activation and degradation are expressed in several
areas of the brain involved in sleep regulation. Vitamin D is also involved in the pathways of production of
Melatonin, the hormone involved in the regulation of human circadian rhythms and sleep. Furthermore, vitamin D
can affect sleep indirectly through non-specific pain disorders, correlated with alterations in sleep quality, such as
restless legs syndrome and obstructive sleep apnea syndrome.
Conclusions: Vitamin D has both a direct and an indirect role in the regulation of sleep. Although vitamin D
deficiency has been associated to sleep disorders, there is still scant evidence to concretely support the role of
vitamin D supplementation in the prevention or treatment of sleep disturbances; indeed, more intervention studies
are needed to better clarify these aspects.