If a patient feels chest tightness when lying down, but the symptoms are relieved after changing position, it is usually necessary to consider cardiogenic diseases, such as coronary artery disease, unstable angina, myocarditis, pericarditis, hypertrophic obstructive heart disease, and heart valve disease, all of which will lead to different degrees of coronary artery ischemia, stenosis, and spasm, and the myocardium will have insufficient blood supply, and the myocardial cells will also have ischemia and lack of oxygen. Therefore, when lying down, there will be obvious symptoms when the coronary artery is compressed, but when standing up, there will be some relief. In addition, for respiratory system diseases, such as chronic obstructive pulmonary disease, chronic bronchiectasis, and pulmonary hypertension, there will also be insufficient blood supply to the pulmonary arteries in this condition, and usually the symptoms will also be aggravated when lying down and relieved when getting up.