Case study: melatonin in severe obesity.

Nocturnal serum melatonin was measured at half-hour intervals from 6:30 P.M. to 7 A.M. in two sisters, one severely obese 15-year-old and one somewhat overweight 12-year-old. Both, otherwise, were physically and psychiatrically healthy. In the severely obese sister, there was a significant increase in the serum melatonin mean level, a delayed phase-shift, and a delayed peak. Also, her overnight urine melatonin and its metabolite, 6-hydroxymelatonin sulfate, were significantly higher. Could there be a relationship between dysregulation of the pineal gland and severe obesity?