Left side pelvic pain that prevents you from sleeping on your side at night may be related to pelvic compression and pulling on tissues such as ligaments around the pelvis. Left side pelvic pain, generally sleep if to the left side lying position, it will compress the left side of the pelvis, so that the pain symptoms worsen. If you sleep on your right side at night, the ligaments and muscles around the right side of the pelvis pull on the left side of the pelvis, which may also cause pain. When pain occurs, the patient is usually forced to choose the flat position, so that both sides of the pelvis are subjected to the same force can relieve the pain symptoms. If the left side of the pelvis pain at night can not sleep on the side, it is recommended that the patient to go to the hospital to improve the pelvic radiography, CT and other examinations, to clarify the cause of the disease, to receive regular treatment.