The human drive to eat (and to stop when satiated) is largely controlled by hormones. When the body releases the hormone ghrelin, for instance, appetite increases, while the release of leptin (typically after a meal is consumed) dampens appetite. The release of ghrelin and leptin fluctuates throughout the day and is influenced by the body’s circadian rhythm, the timing of the last meal, and how much food is eaten. However, poor sleep, stress, or other physiological factors may lead to increases or decreases in hormone amounts that can disrupt appetite.