Participants in this study will be randomly assigned (as in the toss of a coin) to one of two treatment groups. Participants in one group will receive melatonin. Participants in the other group will receive a placebo. A placebo is a substance that looks like the study drug, but which has no active ingredients. There is an equal chance of being in either group. Neither you nor the study doctor will know to which group you are assigned. You will take either two, three, or four capsules 30 minutes before you go to bed. You will go to bed at about the same time each day (around 10:00PM). The number of capsules will be prescribed according to your body weight.