A heart attack when fast asleep may be a physiological reaction caused by nightmares during sleep, or it may be due to the presence of heart disease, such as insufficient myocardial blood supply, cardiac arrhythmia, obstructive hypertrophic heart disease, mitral stenosis and other diseases. If there is no panic, chest tightness, swelling of both lower limbs, wheezing after activity, hemoptysis, coughing pink foamy sputum, chest pain, paroxysmal dyspnea at night and other manifestations are generally not a big problem. If the above-mentioned discomfort occurs frequently, it is necessary to seek timely medical attention to improve the relevant tests and actively treat the disease with medication, such as compound salvia drops and quick-acting heart pills, to prevent the irreversible consequences of the aggravation of the disease.