Seasonal Levels of Melatonin, Thyroid Hormones, Mood, and Cognition Near the Arctic Circle

Abstract

Associations between serum melatonin and thyroid hormones with mood were consistent with the psychological changes associated with the polar triiodothyronine syndrome. Also, serum melatonin and thyrotropin were associated with impaired and fT3 with improved cognitive performance, supporting the decrements in cognitive performance associated with the polar triiodothyronine syndrome.