Sore calves at night may be caused by strenuous exercise, poor blood circulation, varicose veins and other reasons. 1. Strenuous exercise: such as running for a long time, lifting the legs and other strenuous exercise, can make the muscle metabolism produce a lot of lactic acid, which can appear lactic acid accumulation, causing the phenomenon of calf soreness in the evening. 2. Poor blood circulation: when blood vessel elasticity decreases and blood clots occur in the lower limbs, it can cause poor local blood circulation and insufficient local nutrition, which leads to the symptom of sore calves at night. 3. Varicose veins: it means that the veins appear to be bulging, expanding, tortuous and other manifestations. When varicose veins appear in the lower limbs, the patients mostly have the feeling of discomfort and pain, i.e. the symptom of sore calves when sleeping late. It is recommended that patients with sore calves at night should go to the hospital in time and follow the doctor’s instructions to avoid delaying their condition.