[The nyctohemeral rhythm of melatonin is preserved in human African trypanosomiasis]

We studied plasma melatonin profiles by radioimmunoassay in nine patients suffering from human african trypanosomiasis and six healthy controls matched according to the age and the photoperiodic conditions. The circadian periodicity of the sleep-wake cycle was disturbed proportionally to the degree of severity of the disease. On the contrary, the patients' plasma melatonin profile was similar to the controls' one. These results suggest that, beside the master clock generating the main circadian rhythms (sleep-wake, melatonin and core temperature rhythms), an additional regulating system of the melatonin rhythm could be involved.