Although our results do not provide a mechanistic explanation for this finding, we speculate that the lack of a relationship between sleep parameters and active TGF-β1 levels in obese patients with OSA might be attributable to the obesity-induced activation of the NFkB pathway, which could attenuate the OSA-induced HIF-1α -TGF-β production pathway. This evidence concerns the gene TGFB1 and obesity due to melanocortin 4 receptor deficiency.