If you have chest pain when sleeping on your side at night, you must first exclude whether there are heart problems, such as angina pectoris or myocardial infarction, and go to the hospital to have an electrocardiogram or a blood test for troponin, which can basically confirm the diagnosis. If cardiac problems are excluded, it is usually thoracic costochondritis, which is caused by inflammation of the cartilage inside the thoracic rib joints, and there will be localized pressure and pain, which will be aggravated or appear when taking a deep breath or exerting the thorax or exercising. Usually when sleeping at night, when sleeping on the side, the force will be transmitted to the place of the thoracic rib joint will also induce its pain. Generally, you can take non-steroidal anti-inflammatory drugs orally to eliminate local inflammation, and apply ointment that reduces swelling and relieves pain, invigorates blood circulation and removes blood stasis externally, and the symptom can be improved soon.