If patients suddenly feel out of breath while sleeping, there are usually the following factors: 1. Cardiogenic factors, such as heart atherosclerotic heart disease, unstable angina, or cardiac arrhythmia, acute myocarditis, pericarditis, infective endocarditis, hypertrophic obstructive cardiomyopathy and other cardiac insufficiency, can occur when sleeping suddenly out of breath. 2, some respiratory system diseases, such as chronic bronchitis, bronchiectasis, chronic obstructive pulmonary disease, chronic heart failure, respiratory failure, serious patients such as pulmonary heart disease, pulmonary hypertension, will also appear in the sleep suddenly out of breath clinical symptoms. The above symptoms should be treated with oxygen immediately, while going to the hospital for systematic treatment.