Sinus bradycardia is commonly associated with intracranial disorders, hypothyroidism, obstructive jaundice, etc., but it is normal for some athletes to experience sinus bradycardia. Sinus bradycardia is mainly associated with physiologic and pathologic states and is not necessarily a precursor to certain diseases. Sinus rhythm is generated mainly from the sinus node, and the frequency of sinus rhythm is usually 60~100 times/minute. Abnormalities in the frequency of sinus node impulses or arrhythmias caused by blocked conduction of sinus impulses to the atria can lead to sinus tachycardia, sinus bradycardia, sinus arrest, sinus block, and sick sinus node syndrome. Sinus bradycardia, clinically known as sinus bradycardia, is a sinus rhythm with a frequency of less than 60 beats per minute, and its causes are more complex and include the following: 1. Healthy young people and athletes may have sinus bradycardia, and sometimes sleep states can also trigger sinus bradycardia; 2. Pathologic sinus bradycardia is mainly seen in intracranial disorders, severe hypoxia, hypothermia, hypothyroidism, obstructive jaundice and other diseases; 3. Sinus bradycardia can also be induced by certain drugs, such as cholinergics, amiodarone, beta-agonists, and non-dihydropyridines. Therefore, sinus bradycardia can be triggered by physiological factors, as well as by pathologic factors or medications, and is not necessarily a precursor to a particular type of disease.