Having observed that Hypoxia Inducible Factor(HIF)-1a-subunit and Vascular Endothelial Growth Factor (VEGF) are conversely correlated with hypoxia indices in OSA patients30,31, and given the existing association between vD, HIF-1a-subunit and VEGF in human cancer cells but also the noted downregulation of HIF-1a-subunit, VEGF after CPAP treatment, those factors may also contribute to the lower vD levels of OSA patients27. Here, HIF1A is linked to obstructive sleep apnea syndrome.