Night eleven to three in the morning back and leg pain may be caused by strenuous exercise, may also be lumbar disc herniation, pear-shaped muscle syndrome and other diseases. 1. Strenuous exercise: such as strenuous exercise during the day, can lead to lactic acid buildup, will cause local muscle soreness, which may lead to lumbar and leg pain at night. 2. Lumbar disc herniation: refers to the prolapse of nucleus pulposus tissue from the ruptured annulus fibrosus of the lumbar intervertebral disc, which is mainly manifested as lumbar pain, radiating pain in the lower limbs, numbness in the lower limbs and other symptoms, and may also lead to nighttime pain in the lower back and legs. 3. Piriformis syndrome: It is caused by the damage to the piriformis muscle that compresses and stimulates the sciatic nerve. Its main manifestation is buttock pain and lower limb radiating pain, can be accompanied by lower limb numbness, weakness, claudication and other symptoms, can also lead to lower back and leg pain at night. There are many other causes of nocturnal pain in the lower back and legs, which should be emphasized, timely consultation, identification of the cause of the disease, and further treatment or treatment in accordance with medical advice.