BUHLMANN Chronobiology - Melatonin - 6-Sulfatoxymelatonin



Melatonin, the major hormone secreted by the pineal gland, is a key modulator of seasonal and circadian biorhythms. The synthesis and secretion of melatonin is controlled by a circadian clock in the hypothalamus and is synchronized by the light-dark cycle.


The principal metabolite of melatonin is 6-sulfatoxymelatonin. The particular advantage of measuring 6-sulfatoxymelatonin is the ability to assess pineal function by urine sampling, since urine contains only traces (approx. 1%) of non-metabolized melatonin. The measurement of 6-sulfatoxy-melatonin in urine provides a non-invasive, integrated parameter by which circadian rhythms can be assessed over a period of time.