If a hypertensive patient has high blood pressure at 4:00 a.m., consider whether he or she is taking antihypertensive medication regularly. If the blood pressure is still high when taking antihypertensive drugs regularly as prescribed by the doctor, consider that the current antihypertensive drugs are not effective and you need to go to the hospital to adjust the antihypertensive program. After adjusting the antihypertensive regimen, you need to monitor your blood pressure regularly. If blood pressure is not normally high and is high at 4:00 a.m., there may be improper rest, and the most appropriate time to measure blood pressure after adequate rest is early in the morning after emptying the bladder and maintaining emotional stability and quietness. It can be done in the morning from 6-8 am and in the afternoon from 4-8 pm, because there is a peak in each of these two time periods. Most people have the lowest blood pressure at 2-3 am, with a slow downward trend from 8 pm. If blood pressure continues to increase at night and antihypertensive drugs are not effective, secondary hypertension, such as increased blood pressure caused by kidney disease, needs to be excluded. Or adjust the time and dose of antihypertensive drugs according to the situation.