In regard to correlations between evening and morning circadian clock protein levels, in the OSA group, they were found for CLOCK (R = 0.600, p < 0.001), CRY1 (R = 0.440, p < 0.001), and PER1 (R = 0.583, p < 0.001)—all are statistically significant—but not for BMAL1 (R = 0.057, p = 0.68). This evidence concerns the gene PER1 and obstructive sleep apnea syndrome.