Lying for a long time leg weakness may be caused by overwork, but also the performance of many diseases, such as lumbar disc herniation, hip joint lesions. 1. Overwork: healthy people if suddenly overworked or too much exercise, sleep will lead to a lot of lactic acid buildup in the muscles, resulting in weak legs, soreness. 2. Lumbar disc herniation: the main symptom is lumbar pain, unfavorable activities, serious compression of the sciatic nerve, resulting in hip, lower limbs, feet, radiating pain, lying down, may be due to the mattress is too soft, resulting in excessive load on the intervertebral discs, resulting in severe nerve compression, may appear to lie down for a long time the symptoms of the leg is not strong. 3. Hip joint lesions: such as femoral head necrosis, hip osteoarthritis, rheumatoid arthritis, ankylosing spondylitis. After the occurrence of lesions, serious cases can lead to leg weakness. Repeatedly lying down for a long time the phenomenon of leg weakness should be timely to the hospital, improve the examination to clarify the cause of the disease, follow the doctor’s instructions to give targeted treatment, so as not to delay the condition.