Interindividual Differences in the Responses of Serum and Salivary Melatonin to Light

Abstract

Several studies in the late seventies characterized insensitivity to light as a feature of human melatonin synthesis. Later it hàs shown that bright light does suppress human melatonin secretion (Lewy et al. 1980). More recently it has been reported that even lower illuminances decrease the nighttime melatonin levels in humans (e.g. Bojkowski et al. 1987, McIntyre et al. 1989a). Technical and experimental differences may serve as an explanation for the deviating results. It is also possible that interindividual differences of sensitivity obtained from small groups of subjects distort the results. In the present preliminary study we attempted to find such individual differences.