Urinary 6-sulphatoxy melatonin excretion during the human menstural cycle

The excretion of 6-sulphatoxy melatonin in urine has been shown to provide a reliable index of melatonin production in man. Daily measurements made in two healthy ovulating women showed that both the total amount excreted/day and the proportion excreted during the sleep period remained relatively constant for each subject throughout the menstrual cycle. These data do not support the view that there are changes in melatonin production which correlate with cyclical reproductive endocrine function in the human.