The causes of weak legs at night are sports factors, cold lower limbs, electrolyte disorders and so on. 1. Exercise factors: due to too much exercise during the day or incorrect posture during exercise, the leg muscles are more active during the day, consuming too much energy, and when resting at night, due to the low supply of energy, there will be symptoms such as leg weakness, weakness and so on. 2. Cold lower limbs: due to the lack of warming measures in place at night, the lower limbs are cooled, resulting in muscle tissue in a tense state, the local blood flow is reduced, resulting in a decrease in the energy supply of the lower limbs, triggering patients to experience symptoms of leg weakness. 3. Electrolyte disorders: due to the lack of potassium and calcium in the patient’s body, resulting in electrolyte disorders in the body, triggering the nerve conduction function of the whole body’s muscular tissues, which leads to the symptoms of leg weakness in the patient. There are many reasons why patients experience weakness at night, and it may also be related to cervical spondylosis, lumbar spinal stenosis, etc. It is recommended that patients go to the hospital in a timely manner, complete the relevant examinations, clarify the cause of the disease, and comply with the doctor’s instructions for treatment.