The measure to minimize the risk, fully inform the participants and their families the trial's advantages, disadvantages and desired effect. All participants totally agree with the subjects. In this process, at least three or more effective way to get contact with the medical staff or doctor and ensure that those unexpected accident should deserve effective tackle. Examination for every participant before start of the trial to guarantee they comply with the criterion. Our research involves the application of melatonin is through the china food and drug administration (CFDA) approved to ensure its safety (include its chemical composition, structure, content parameters, main raw material and appropriate crowd). All staff is qualified medical professionals to guarantee the safety of all participants.