White coat hypertension is no longer considered a benign state but a pathologic response, an elevation of blood pressure in a specific environmental state, just as many patients present to the hospital with high blood pressure while their home self-measured blood pressure is normal, but can develop into persistent hypertension over a period of time. If such patients are also combined with obstructive sleep apnea, 42.8% of them develop persistent hypertension after about 2 years. Therefore it is quite important to diagnose and treat sleep apnea in a timely manner.