Arrhythmias that occur during sleep may be triggered by the occurrence of premature beats. In addition, there may be paroxysmal atrial fibrillation or atrial flutter, which can also cause the patient to have an arrhythmia. In addition to identifying what type of arrhythmia the patient has, it is most important to identify the cause of the arrhythmia, such as whether it is due to an ionic disorder, abnormal thyroid function, anemia, cardiomyopathy, heart failure, or myocardial ischemia. All of these causes may lead to arrhythmias during sleep, and patients are advised to undergo cardiac ultrasound and ambulatory electrocardiography if necessary. If it is only episodic premature beats, no special treatment is usually needed, but if frequent atrial fibrillation or atrial flutter, transient ventricular tachycardia or supraventricular tachycardia occur, relatively these problems are more serious.