Blood pressure fluctuates greatly, low in the morning and high in the afternoon may be a normal phenomenon, may also be related to taking antihypertensive drugs, or work. 1. Normal physiological reasons: blood pressure itself has a certain periodicity, rhythmic changes, usually in the morning due to the evening rest after the blood pressure is lower, in the afternoon due to exercise or work after the blood pressure rises, the lowest is about 2:00 to 3:00 in the morning. If the blood pressure does not exceed the normal range throughout the day, it is a normal phenomenon and there is no need to worry. 2. Drug factors: hypertension patients taking antihypertensive drugs may lead to low in the morning, high in the afternoon, and fluctuations in the range of large, such as taking some short-acting antihypertensive drugs, take the blood pressure will soon be reduced, and then after the effect of the drug blood pressure began to rise, this situation needs to take a long-lasting antihypertensive drugs, to maintain stable blood pressure. 3. Work factors: Whether it is mental labor or physical labor, most people have enough energy or physical strength in the morning, which has little effect on blood pressure, and will feel tired in the afternoon, resulting in varying degrees of blood pressure, relatively speaking, blood pressure fluctuations. Blood pressure fluctuations should be timely medical care, under the guidance of the doctor to clarify the specific reasons for life, psychology, work and medication adjustments.