Most people have high blood pressure levels during the day from 6-10 am and 4-6 pm. Some people also have high blood pressure at night, so it is not possible to generalize. Human blood pressure is constantly changing, and there can be transient fluctuations of more than 10 mmHg in a normal person’s blood pressure. Under normal physiological conditions, human blood pressure is “double peaks and valleys” within 24 hours, with periodic rhythmic changes in the shape of a ladle, and its basic law is that the blood pressure is low at night, about 10% lower than that of the daytime, and is at its lowest point at 3 o’clock at night. The reason for the nocturnal drop in blood pressure is partly due to the phenomenon of increased activity of the parasympathetic nerves, and partly due to a decrease in the output of the sympathetic nervous system. Basically, blood pressure is at a relatively high level during the day, with two peaks occurring between 6-10 am and 4-6 pm. From 6 p.m. onwards, the blood pressure slowly decreases, which is called “ladle” blood pressure because it resembles a long-handled ladle. However, it should be noted that some patients may have abnormal circadian rhythm of blood pressure, and the average blood pressure at night is higher than that during the day, which is called “anti-pryoid” blood pressure. Therefore, the time of day when a person’s blood pressure is higher has a certain degree of individual variation, which can be clarified through 24-hour blood pressure monitoring. In case of abnormally high blood pressure, it is necessary to go to the hospital in time and take treatment according to the doctor’s advice to avoid delaying the condition.