When the normal heart contracts, it carries blood through the arteries to the organs of the body to supply them with nutrients. The pressure exerted on the walls of the blood vessels as the blood passes through them (called systolic pressure) and the pressure exerted by the vessels to keep the blood flowing forward (called diastolic pressure). We can measure blood pressure using a sphygmomanometer at —-. Blood pressure varies in a circadian rhythm in both healthy and hypertensive people. During the day the body is more active, the body needs more oxygen and nutrients, and accordingly needs a lot of blood pressure to be delivered, the blood pressure is higher. At night, when the body sleeps, it requires minimal oxygen and nutrients, and the blood pressure is lower. Seasonal and environmental changes can also cause blood pressure to fluctuate, with winter blood pressure generally being higher than summer. Also exercise, emotions, etc. can affect blood pressure fluctuations. The ideal blood pressure is generally a normal adult (>20 years old) with blood pressure <120/80mmHg. The current definition of hypertension is mainly defined as systolic blood pressure >14mmHg and diastolic blood pressure >90mmHg considered as hypertension when upper limb blood pressure is measured 3 times on non-same day without the use of antihypertensive drugs. Hypertension is insidious, most patients are usually asymptomatic and do not even know they have high blood pressure, and many of them are only discovered during physical examinations or occasional blood pressure measurements, so hypertension is also known as the “invisible killer”, and cardiovascular disease deaths are generally related to hypertension. Some patients are only aware of their high blood pressure after a heart attack or stroke, so it is recommended that the family should measure blood pressure at least once every two years; and those who are prone to hypertension should have their blood pressure measured once every six months for early detection of hypertension.