Blood pressure is not the same in the morning as it is in the afternoon, and blood pressure values fluctuate throughout the day. Blood pressure is the lateral pressure of the blood in a blood vessel against the vessel wall, usually referred to as arterial blood pressure, measured mostly in the brachial artery. Because blood circulates in the body, the lateral pressure of blood on the walls of blood vessels, i.e. blood pressure, varies at different times. Blood pressure depends mainly on the output of the heart and the resistance of the peripheral blood vessels of the body circulation; to observe the changes of blood pressure at different moments, you can use ambulatory blood pressure monitoring, for normal people, blood pressure shows a clear circadian rhythm, manifested as double peaks and valleys, there is a peak in the morning at 6~10 am and a peak in the afternoon at 4~8 pm, while the blood pressure at night is significantly lower. Normal blood pressure is <120 mmHg systolic and <80 mmHg diastolic, with high values of 120-139 mmHg systolic and/or 80-89 mmHg diastolic. although blood pressure fluctuates, three measurements of systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg on a day other than the same day are diagnostic of high blood pressure, and treatment is required accordingly. Treatment. If you notice any abnormality in your blood pressure or any discomfort, please consult your physician to avoid delaying your condition.