Sudden foot pain at night may be caused by cold feet, lactic acid buildup, muscle strain, lumbar disc herniation and other reasons. 1. Cold feet: If you don’t pay attention to keep warm when you sleep at night, your feet will get cold, which will lead to local vasoconstriction and symptoms such as foot pain and cramps. 2. Lactic acid accumulation: If the activity is too strenuous during the day, it may produce more lactic acid accumulation within the muscles, which will affect the normal excretion of lactic acid when sleeping at night, and sudden foot pain will occur. 3. Muscle strain: If you are overactive during the day, it may lead to muscle strain and sudden foot pain when you sleep at night. 4. Lumbar disc herniation: when the patient has lumbar disc herniation, it will easily lead to nerve root compression in the spinal canal, causing nerve compression in the innervated area of the foot, sudden foot pain at night, accompanied by numbness and other discomforts. Sudden foot pain at night, it is recommended that the earliest possible hospital examination to clarify the cause of the disease under the guidance of the doctor active treatment, so as not to delay the condition.