Asymptomatic in daytime but occurs hidden pain in kidney at night may be caused by lumbar muscle strain, stones, kidney tumors and so on. 1. Lumbar muscle strain: when the lumbar region carries out weight-bearing exercise for a long time, the lumbar muscle becomes fibrous and inflammation occurs, causing lumbar muscle strain, which stimulates the peripheral tissues of the kidneys, and the kidneys may have hidden pain. 2. Stones: when you sleep at night, kidney stones may stimulate the surrounding tissues, and the kidneys may also have hidden pain. 3. Kidney tumor: when the kidney tumor presses on the kidney or damages the kidney, hidden pain may also appear in the kidney. Patients who are asymptomatic during the day but experience hidden pain in the kidney at night should go to the hospital in time to get a clear picture of the cause of the disease under the guidance of a physician and get timely treatment.