The most common factor is chronic obstructive pulmonary disease, often due to chronic bronchitis, chronic bronchial dilatation, chronic obstructive emphysema, chronic pulmonary heart disease, pulmonary hypertension and a series of other diseases that lead to inadequate alveolar ventilation, so there will be lung function, lying down due to ventilation, ventilation and respiratory arrest, so lying down to sleep will appear more 2, but also and cardiac insufficiency, cardiovascular blood supply is insufficient, the heart blood supply capacity is weakened, the aorta blood supply insufficiency when lying down leads to a relative reduction in the amount of cardiac blood return, lying down at night when sleeping will appear uncomfortable clinical symptoms and performance.