PER1 and obstructive sleep apnea syndrome: We also found mRNA levels of Bmal1 and Dec1 were significantly increased in the OSA with hypertension group (blood pressure ≥130/85 mmHg) compared to the OSA without hypertension group (blood pressure <130/85 mmHg, p < 0.001 for Bmal1 and p < 0.01 for Dec1), while no significant difference for Per1 was found between these two groups (Figure 4B).