Under normal circumstances, a heart rate between 40-50 beats/min is considered bradycardia and is pathological. If you are in a sleep state, or some special people, such as those who perform heavy physical work on a daily basis, athletes, etc., the heart rate may be between 40-50 beats/min, which is normal. The average heart rate of normal adults is about 75 beats/min at quiet time, i.e. 60-100 beats/min, but it can exceed 100 beats/min during exercise or be lower than 60 beats/min during sleep, and there are fluctuations. Generally, if the heart rate is lower than 60 beats/min at quiet time, it can be considered as bradycardia. If it is accompanied by dizziness, transient darkness, weakness, palpitations, chest tightness and other symptoms, it should be paid enough attention. You should visit your local hospital and get a 24-hour ambulatory ECG or cardiac ultrasound to understand the heart condition. In addition, there is a special category of cases, athletes due to year-round training, better cardiopulmonary function, more cardiac output each time, then the heart rate is slower, is a normal physiological phenomenon, do not worry too much. If diagnosed by a doctor as bradycardia, you should follow the doctor’s instructions to improve the relevant tests to clarify the cause of the disease and the corresponding treatment. You should also pay attention to regular work and rest and adequate nutrition.