How are VDR and sleep related?

The vitamin D receptor (VDR) is a nuclear receptor activated by calcitriol, the active form of vitamin D. VDR is expressed in many tissues, including brain regions involved in sleep regulation (e.g., hypothalamus). Mechanistic studies suggest VDR influences genes related to melatonin synthesis and circadian rhythm. Some human association studies link VDR polymorphisms (e.g., rs2228570, rs1544410) to sleep traits like duration, latency, or quality. However, effect sizes are small, findings are inconsistent across populations, and many studies lack replication. Vitamin D deficiency is also associated with sleep disorders, but causality remains unproven. Caveat: Evidence is primarily mechanistic and associative; personalized sleep advice based on VDR genotype is not clinically validated. A blood vitamin D test is more actionable than a genetic test for sleep concerns.