There are many reasons why dyspnea can be caused by lying down on one’s side, which may be caused by long-term side-lying habits, or by diseases, including tongue thrust, occupational lesions, and so on. 1. Tongue falling back: it can be seen in congenital small jaw and mandibular fracture. When lying down, the tongue moves backward and blocks the pharyngeal cavity, resulting in dyspnea, which can be relieved after lying on the side. 2. Occupational lesions: such as goiter in the neck, goiter will compress the trachea, so the dyspnea can be relieved when lying on the side, and the dyspnea will disappear. Surgery is usually used to treat this condition. If there is lying down to sleep dyspnea side lying on the good, there may also be other reasons, it is recommended that patients go to the hospital in a timely manner, to clarify the cause of the disease, under the guidance of the doctor for treatment.