Whether or not a heart rate of 40-50 beats/min during sleep is normal depends on the patient’s specific situation and cannot be generalized. There are significant individual differences in the heart rate of a normal adult at rest, usually 60-100 beats/min, with an average of about 75 beats/min. If the heart rate is 40-50 beats/min during sleep, the heart is bradycardic. In athletes, due to long-term exercise, the heart and lungs are very strong, and the heart bleeds more than the average person per transfusion, even if the heartbeat is only 40-50 times per minute, it is usually normal. However, if an ordinary person without long-term exercise has a heart rate of only 40-50 beats per minute, it is a slow heart rate and needs to be taken seriously. If the patient’s heartbeat is 40-50 beats/minute in the sleeping state with no obvious symptoms, it can be observed. If symptoms such as daily accompanied by dizziness, palpitations, weakness, transient darkness and chest tightness occur, it is recommended to visit the cardiovascular medicine department of the local hospital.