• To test for a proportional gender difference in circadian status (free-running versus entrained) in blind children and in adolescents, a chi-square test of significance will be used for each age group. [ Time Frame: November 1, 2012 ] [ Designated as safety issue: No ]
  
• We will utilize a binomial test to determine the efficacy of melatonin in entraining free-running blind children by examining the percentage of participants who entrain to 0.5 mg of melatonin. [ Time Frame: November 1, 2012 ] [ Designated as safety issue: No ]
  

Subjects will be asked to collect saliva samples in their home hourly throughout the daytime, approximately every 2 weeks. Subjects whose body clocks are found to not be synchronized (entrained) to the 24-hour day (those who have free-running rhythms), will take placebo or melatonin (0.5 mg-1.5 mg). If this dosage of melatonin is successful, subjects will be observed less frequently (every 4 to 6 weeks) to ensure the melatonin continues to work. These subjects may be monitored for up to a year, after which they will be discontinued from the study. If subjects are found to be naturally entrained to the 24-hour day, they will be monitored longitudinally for changes. These subjects may also be monitored for up to one year. Subjects will be discontinued after their monitoring period is over or after an entrained status has been confirmed. All subjects will take placebo or melatonin during their participation and will not know at any time which they are taking. While no specific time commitment is required, we hope most subjects will participant for 4 months - 2 years.