Sinus arrhythmia, the most common cause of which is instability of the nerves that regulate the heart, referred to as the autonomic nervous system. This instability leads to sinus arrhythmia, which is commonly seen in children during their growth phase, women during menopause, or individuals who often stay up late and are under significant work stress, leading to dysfunction of the autonomic nervous system. It can also be caused by patterns of breathing that lead to arrhythmias; the heart rate increases during inhalation and slows during exhalation, producing this type of physiological arrhythmia. Generally, this kind of arrhythmia does not require drug treatment. By improving physical exercise, ensuring adequate sleep, and avoiding stimulating beverages or coffee, this type of heart rate can return to normal.