Positive face up to sleep back pain, that is, lying down to sleep back pain, may be and lumbar disc herniation, lumbar muscle strain, ankylosing spondylitis and other diseases, but also may be due to the mattress is too hard and other causes of physiological back pain. Suffering from lumbar disc herniation, the protruding disc compresses the spinal cord, nerve root will cause lumbar pain, if the lumbar posture is abnormal when lying down to sleep, the nerve root is stretched and strained, the symptoms of lumbar pain will be aggravated. Lumbar muscle strain injury when lying down the damaged muscle fibers are overstretched will also cause pain symptoms. Ankylosing spondylitis involves the sacroiliac joints in the early stage, and in the later stage, it can involve the whole spine, which mainly manifests as resting pain and morning stiffness, and there can be symptoms of severe pain when sleeping. There may also be non-disease-induced, such as mattress is too hard, or the bed surface is not flat, lumbar tissue pressure caused by physiological low back pain, generally can be relieved after getting up. There are other causes of low back pain when sleeping face up, such as trauma, urinary system diseases, etc., if the persistence of non-relief, it is recommended to go to the hospital for medical examination, to clarify the cause of the disease and then follow the doctor’s instructions for targeted treatment, so as to avoid delays in the condition.