Can Vitamin D 25-OH help with sleep?

Whether vitamin D (25-hydroxyvitamin D) can improve sleep is not clearly established by current evidence. Observational studies have linked low vitamin D levels with sleep disturbances, shorter sleep duration, and poorer sleep quality. Vitamin D receptors are present in brain regions involved in sleep regulation, providing a plausible mechanistic link. However, robust randomized controlled trials demonstrating a causal effect of supplementation on sleep are lacking. The existing evidence is mostly mechanistic or associative, not interventional. Additionally, other factors such as iron deficiency (low ferritin) or stress can affect sleep – and these were not connected to vitamin D in the provided contexts. Supplementation should only be considered if deficiency is confirmed, as high doses can be toxic. Overall, the evidence for a sleep-promoting effect of vitamin D is weak to mixed. Without direct studies from the given context, the answer remains conservative.