In mild cases of myocarditis, there are no obvious typical symptoms while sleeping. However, for severe myocarditis or acute attacks of fulminant myocarditis, patients will have certain symptoms during sleep, such as fever, peripheral lethargy, muscle aches, poor sleep function, poor sleep quality, nausea, vomiting, acid reflux, and abdominal distension. In addition, patients may experience paroxysmal sleep dyspnea, accompanied by palpitations, chest tightness, and shortness of breath. Some patients are unable to sleep flat on their back and are able to breathe in a sitting position and have symptoms of coughing cough, phlegm cough, and pink frothy sputum. Severe patients will also have symptoms of left heart failure and will also have varying degrees of wheezing, cyanosis, and other symptoms and states during sleep. In more severe cases of fulminant myocarditis, clinical manifestations such as hyperthermia and increased body temperature during sleep may also occur.