What happened to the weakness of the arms and legs when I woke up? There are several reasons for the weakness of hands and feet when waking up: first, physiological reasons, that is, if people suddenly wake up, the excitability of the human cerebral cortex is not enough, the muscles are very relaxed, the parasympathetic nerves are still in a dominant position, the sympathetic nerves are not excited enough, so the muscle tone of patients is low, people often feel no force. But generally after waking up for a few minutes, slowly as the muscle tone of the limb recovers, the muscle strength gradually returns to normal, which is a physiological phenomenon. The second pathological phenomenon, the most common one is stroke after waking up, when the patient wakes up and suddenly feels the weakness of one limb, it is often caused by cerebrovascular infarction.