Circadian Rhythms and Sleep in Familial DSPS and ASPS

Inclusion Criteria for ASPS Participants: * Morning type score on the Horne-Ostberg questionnaire * Advanced melatonin onset Inclusion Criteria for DSPS Participants: * Evening type score on the Horne-Ostberg questionnaire * Delayed melatonin onset Inclusion Criteria for Controls: * A stable sleep/wake pattern with a normal phase relationship to the environment and no history of sleep disorders Exclusion Criteria for all subjects: * Sleep disorder, other than DSPS or ASPS, as assessed by the Pittsburgh Sleep Quality Index and/or by polysomnogram * History of cognitive or other neurological disorders * History of Diagnostic and Statistical Manual-IV criteria for any major psychiatric disorder, alcohol or substance abuse * Abnormal mood as assessed by the Hamilton Depression Scale * History of, or concurrent, unstable or serious medical illness * Current use of psychoactive medications, including antidepressants, anxiolytics, neuroleptics, anticonvulsants, hypnotics, and stimulant medications * Shift work * Having a daily caffeine intake greater than 4 cups per day * Smoking * Travel across more than 2 time zones within 90 days of the study * Pregnancy or the desire to become pregnant during the study period