The weakness of the legs after waking up in the morning may be related to the following causes: 1, there may be internal joint damage, if the patient has damage to the cartilage and meniscus inside the knee joint, it may cause the symptoms of weakness of the lower limbs when waking up in the morning. 2, it may be related to osteoporosis, some elderly people who suffer from osteoporosis often have weakness of the lower limbs after waking up in the morning, and there may be soreness in the lower limbs and lumbar spine. 3.It may be caused by inflammation of joints involving the whole body, for example, when rheumatism or rheumatoid arthritis attacks, it may involve many joints of the whole body, with the lower limbs being the most important, and when they get up in the morning, the symptoms are heavier, which can produce sleepy legs and weakness. 4.It may also be caused by overexertion, for example, the patient has done too intense This may lead to muscle strain or lactic acid deposition in the lower extremities, which may produce the symptoms of leg sleepiness after a sleep.