The first ability is a hormone cycle that reduces the body's urine production. At about sunset each day, the body releases a minute burst of antidiuretic hormone (also known as arginine vasopressin or AVP). This hormone burst reduces the kidney's urine output well into the night so that the bladder does not get full until morning. This hormone cycle is not present at birth. Many children develop it between the ages of two and six years old, others between six and the end of puberty, and some not at all.