Sudden heart fluttering during sleep may be due to mental factors, hyperthyroidism, arrhythmia, anemia, etc. It is recommended to treat this symptom by taking medication and psychotherapy according to the cause. 1. Psychological factors: If you have recently felt too much mental stress, you may have insomnia, etc., which is prone to autonomic dysfunction and causes heart discomfort. If you suffer from insomnia, you can take zopiclone, oxazepam and so on. 2. Hyperthyroidism: Increased secretion of thyroid hormones can lead to cause panic, increased heart rate, heart discomfort. Propylthiouracil can be taken orally to inhibit the synthesis of thyroid hormone and treat the disease. 3. Arrhythmia: Various types of arrhythmia can cause heart discomfort, which can be treated with medication or surgery, such as bisoprolol, amiodarone, propafenone, and so on. 4. Anemia: Anemia can cause lack of oxygen supply and lead to anemic heart disease. The type of anemia should be clarified and treated, e.g. taking iron, folic acid and vitamin B12. Patients are advised to seek prompt medical attention, and medications should be used under the guidance of a physician. Prompt medical attention should be sought.