The possible causes of leg swelling and soreness at night while sleeping include strenuous exercise, deep vein valve insufficiency of the lower extremities, and lumbar intervertebral disc herniation. 1. Strenuous exercise: may be due to the day after strenuous exercise, did not pay attention to the leg relaxation, caused by the accumulation of lactic acid in the legs, the body will sleep at night when the phenomenon of leg soreness. 2. Lower extremity deep vein valvular insufficiency: Lower extremity deep vein valvular insufficiency can cause localized venous blood flow is not smooth, which can also cause leg swelling, and the phenomenon of leg swelling and soreness will appear at night when you sleep. 3. Lumbar intervertebral disc herniation: Because lumbar intervertebral disc herniation oppresses the local nerve roots, it mainly manifests itself as lumbago, radiating pain and numbness in the lower limbs, etc., and there may be swelling and soreness of the legs, which are more obvious when sleeping at night. There may be other reasons for leg swelling and soreness at night, if the symptoms persist or progressively aggravate, it is recommended to go to the regular hospital in a timely manner to improve the relevant examination, to clarify the cause of the disease, and then under the guidance of the doctor to carry out targeted treatment or therapy.