Side dyspnea, sit up all right roughly, may be related to respiratory diseases such as pleural effusion, cardiovascular diseases such as cardiac insufficiency, nasal cavity disease. 1.respiratory system diseases: such as a large amount of pleural effusion on one side, the affected side lying down when the compression of the thoracic cavity leading to increased pressure on the lung tissue, resulting in hypoxia, dyspnea, sit up after the compression of the lung tissue to reduce the symptoms of improvement. Lung malignant tumor leads to lung atelectasis on one side, and chest tightness can be aggravated by lying on the affected side. 2. Cardiovascular disease: coronary heart disease, cardiac insufficiency patients, at night when lying on the side of the increase in the volume of return blood, pulmonary stasis, there will be dyspnea aggravated, sitting up can be improved. 3. Oral and nasal causes: upper respiratory tract infection, rhinitis, nasal mucosa congestion and edema, when lying on the side due to gravity makes the nasal mucosa blood return poor, resulting in nasal congestion, dyspnea, sitting up after the improvement of nasal mucosal reflux, the symptom improved, tonsils, uvula enlargement, will also cause lying dyspnea. Lateral dyspnea may also be seen in other diseases, the need for timely medical care, improve the relevant examination, under the guidance of specialists on the cause of the treatment.