Upper airway obstruction leads to hypoxaemia, hypercapnia and changes in intrathoracic pressure, which, together with frequent sleep arousals, cause sympathetic arousal, increased heart rate, activation of the renin-angiotensin system, and increased blood pressure [33], which in turn develops into left ventricular hypertrophy and heart failure. This evidence concerns the gene REN and left ventricular hypertrophy.