Arrhythmicity in a child with septo-optic dysplasia and establishment of sleep-wake cyclicity with melatonin.

We identified a 3-year-old child with septo-optic dysplasia with arrhythmic activity patterns. To assess whether melatonin could improve rest-activity patterns, 0.1 mg was administered orally at 19:00 hours. After therapy onset, normal rest-activity patterns appeared. These observations show that melatonin can restore normal rhythmicity in the absence of a normally functioning circadian clock.