Evidence check: VDR in the context of Schlaf

The provided context does not include specific information on VDR (vitamin D receptor) and sleep. Therefore, this answer is based on general scientific knowledge. VDR polymorphisms (e.g., rs2228570, rs1544410) have been associated in studies with sleep quality, duration, and disorders like insomnia, likely via circadian rhythm regulation and vitamin D metabolism. However, the evidence is moderate and inconsistent: some studies show associations, others do not. Effect sizes are small and confounded by environmental factors (sun exposure, diet). A single DNA test cannot reliably predict individual sleep patterns. Clinically relevant sleep issues should be evaluated by a physician. Evidence grade: human-moderate (GWAS, but replicated).