Melatonin and thyroid hormones in the cold and in darkness. Association with mood and cognition

Abstract

The purpose of the study was to examine the cold-induced effects on pineal and thyroid hormones as well as the associations of these hormones with psychological performance and to determine how psychological performance could be affected by demographic, anthropometric, physiological or biochemical measures during cold acclimatisation. The feasibility of urinary melatonin (MT), rather than 6-sulphatoxymelatonin (aMT6s), as an indicator of MT secretion was also examined. In the laboratory study, seasonal cold acclimatisation, its effects on hormones and their associations with mood and cognition were assessed in 15 young urban subjects exposed to cold in winter or summer in bright or dim light. In the field study, the associations of mood and cognition with demographic, anthropometric, physiological and biochemical measures were determined in healthy, euthyroid subjects (n = 133) in Antarctica in the beginning and at the end of summer and winter seasons.In both seasons, simple task performance was consisten...