When we compared the levels of the three prohormones in the morning (6–9 a.m., at baseline) and evening (8–10 p.m., before CPAP initiation) in patients with OSA, there was a circadian change in proADM levels, which increased in the evening and in proANP levels, which decreased in the evening (Fig. 3). This evidence concerns the gene NPPA and obstructive sleep apnea syndrome.