Normal physiological heart rate is 40 beats / min, does not need special treatment, disease caused by low heart rate, should go to the hospital immediately. Normal human heart rate is 60~100 beats/min, heart rate 40 beats/min is abnormal. Low heart rate may be caused by physiological factors or pathologic factors. Athletes, heavy manual laborers or the elderly generally have a lower heart rate than normal when they are asleep, and generally do not require special treatment. If it does not belong to the above situations, it may be caused by pathological diseases. Common causes of low heart rate include atrioventricular block, sinus node problems, myocardial ischemia, or systemic metabolic diseases resulting in low metabolism of the human body. Therefore, it is recommended to go to the hospital immediately after the occurrence of low heart rate, to identify the causes of low heart rate, and actively treat the causes of low heart rate.