 The purpose of the proposed study is to determine whether the amount children sleep is associated with changes in hormones, hunger, motivation to eat, and food intake. Fifty children 8-11 years old who sleep 9-10 hours per night will be enrolled for a 3-week study. For 1 week each, children will be asked to sleep their typical amount, increase their sleep by 1-12 hours, and decrease their sleep by 1-12 hours. Half of the children will be asked to increase their sleep first and half to decrease their sleep first. During each week, the following will be gathered: sleep duration measured by actigraphy, which is a small device that measures sleep, levels of hormones measured through blood draws, self-reported hunger and appetite, food intake measured by 3 days of 24-hour recall, how motivated children are to eat measured using a computer activity, and child height and weight. We believe that when children sleep less they will show changes in hormones associated with hunger and appetite, report being hungrier, be more motivated to eat, and eat more food. 