Melatonin sensitivity to dim white light in different seasons

Abstract

It is well known that the pineal hormone melatonin is suppressed by light. The melatonin suppression by dim light has also been suggested as a possible trait marker of bipolar disorder. However, there is large inter individual differences in the light responses. It is possible that methodological factors may contribute to the variable responses observed. Most studies in the past have been conducted in different seasons under different lighting conditions. It is possible the external lighting conditions may affect the melatonin suppression to dim light. Hence we examined the melatonin suppression by dim light in (1) a large group of subjects randomly tested once in one of the four seasons (pa..