Vitamin D supplementation (VDS) holds promise as a way to improve sleep quality, according to a systematic review. However, the author warns that VDS’ effect on sleep quantity and disorders needs to be further investigated.
“The positive effects of VDS could be considered in clinical practice, especially in the context of beneficial skeletal and pleiotropic extraskeletal effects of vitamin D, as well as the relatively limited cost of VDS,” says Myriam Abboud of Zayed University, UAE.
The paper, now published in Nutrients, takes into account 19 studies. There were four pre-post studies, which all showed a “significant” improvement in sleep quality with VDS.
Similarly, the results of the meta-analysis revealed a statistically significant decrease in the Pittsburgh Sleep Quality Index with VDS compared with placebo, with moderate certainty.
However, the results regarding the effect of VDS on sleep-related impairment, difficulty and disorders, as well as sleepiness and restless legs syndrome, were not unanimous.
How does it work?
Although the exact physiological mechanisms between vitamin D and sleep regulation have not yet been fully uncovered, several direct and indirect mechanisms have been suggested.
One potential mechanism is the extensive presence of vitamin D receptors in many parts of the brain, specifically areas that affect sleep, the paper details.
Another theory involves the expression enzymes involved in vitamin D activation and degradation in areas in the brain known to be involved in sleep regulation.
The paper also proposes that there is a link stemming from vitamin D being regulated by sunlight exposure, which in turn, affects the circadian rhythm.
“Furthermore, the production of melatonin is regulated by vitamin D. Thus, impaired vitamin D levels could decrease melatonin levels, potentially leading to sleep disorders,” writes Abboud.
Finally, vitamin D plays a role in downregulating inflammatory markers that are involved in sleep regulation. When people are deficient, such inflammatory markers would be raised, negatively affecting sleep.
Widespread sleep disorders
Abboud notes that inadequate sleep is a common public health problem of significant personal and societal burden. Notably, sleep disorders like insomnia are increasingly being diagnosed in clinical practice.
According to Abboud, it is estimated that 59% of young adults suffer from a sleep disorder and do not get enough sleep, and only 36% of this population reports being free of sleep disturbances.
Addressing an economic burden
Furthermore, Abboud notes that inadequate sleep is an “underappreciated” determinant of health, which can lead to short-term and long-term consequences.
“The economic burden of inadequate sleep is substantial, warranting urgent investment in health measures to address this issue,” she urges.
In tandem, growing evidence suggests that vitamin D deficiency can increase the risk of sleep disorders and is associated with sleep difficulties, shorter sleep duration, and nocturnal awakenings in children and adults.
“Preventing and managing sleep disorders or correcting them by VDS is of public health relevance, given the low cost of this intervention and its effectiveness in other therapeutic areas,” Abboud concludes.
Notably, vitamin D has been in the spotlight throughout the pandemic thanks to its links with better COVID-19 outcomes. It also has a key role in bone health, especially when combined with other ingredients like vitamin K2.
However, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) recently warned of the dangers of vitamin D overdose, especially for infants.
Edited by Katherine Durrell