Unique provision in the American Recovery and Reinvestment Act prevented approval of second year no-cost-extension in which completion of analyses were planned.

The purpose of this study is to learn more about abnormal body rhythms in blind boys and girls that keep them from falling asleep at bed-time or cause them difficulty staying alert during the day. The investigators hope to learn if there are any differences between the body rhythms of girls and boys. The investigators also want to investigate whether age or puberty have an effect on body rhythms.

Subjects will be asked to collect saliva samples in their home hourly throughout the daytime, approximately every 2 weeks. 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. Subjects will be discontinued after their monitoring period is over or after an entrained status has been confirmed. While no specific time commitment is required, we hope most subjects will participant for 4 months - 2 years.

Inclusion Criteria:

• Totally blind
• Between 5-8 yrs or 17-20 yrs of age

Exclusion Criteria:

• Pregnancy
• Light perception
• Low melatonin production
• Taking melatonin
• Co-morbid medical disorders (such as seizure disorders)

The PI has retired from the institution. Sincere efforts were made to contact the PI/study team members, but were unsuccessful. No study data are available.

The PI has retired from the institution. Sincere efforts were made to contact the PI/study team members, but were unsuccessful. No study data are available.

Technical problems with measurement leading to unreliable or uninterpretable data; Consistently could not obtain a complete melatonin profile from participants' saliva samplings and thus could not determine melatonin onset.