When sleeping on your side, you will often wake up with chest pain, which is relatively common in the clinical situation. The specific reasons include the following: 1, due to the incorrect posture of the side sleep, gravity or body weight completely pressed in the chest, it will cause a certain amount of local back at the chest, or soft tissue extrusion. If you sleep on your side for a long time, the intercostal nerve muscles and cartilage in the chest will be squeezed, and the pain will be obvious after waking up. 2, some underlying diseases, such as intercostal neuralgia, or non-specific infection of intercostal neuritis, may stimulate the intercostal nerve endings when sleeping on your side, and the pain will be obvious after waking up. 3, with hypertension, coronary artery disease. In incorrect sleep position or side, sleep easily induced angina pectoris, or coronary syndrome, causing chest pain. When these symptoms occur, it is important to go to a regular hospital for a detailed examination to find the exact cause of the disease and to carry out systematic treatment for the cause.