A large day-to-day difference in heart rate may be due to factors such as exposure to emotions, diet, lifestyle, sleep, or pathological factors such as cardiovascular disease and systemic causes. Normal adult quiet heart rate is 60 to 100 beats / min, and adults exist in excitement, agitation and other emotions or drinking alcohol, strong tea, coffee, there may be sinus tachycardia, the heart rate can be more than 100 beats / min, but generally will not exceed 160 beats / min. Sinus bradycardia may also occur in healthy people who have been engaged in long-term physical labor, as well as in athletes, with a quiet heart rate that is usually less than 60 beats/minute, but more than 45 beats/minute. In the sleep state, due to the increased vagal tone, can also be manifested as sinus bradycardia, the heart rate can be around 50 beats / min, there are also a few people can appear in the heart rate of about 40 beats / min. If you suffer from hypertensive heart disease, coronary heart disease, valvular disease, cardiomyopathy, rheumatic heart disease and other cardiovascular diseases, you may also experience a large one-day difference in heart rate. It may also be related to systemic causes such as toxic effects of drugs, dysfunction of nerve and fluid regulation, and electrolyte disorders. Other organ diseases, such as hyperthyroidism and stroke, can also induce a large day-to-day difference in heart rate. It is recommended to pay more attention to the changes of their own heart rate, if there is an abnormal heart rate also need to identify the causes, timely medical care, if the disease is caused by, should be actively treated.