Sunshine, serotonin, and skin: a partial explanation for seasonal patterns in psychopathology?

A number of studies indicate that there can be seasonal variations in the expression of psychiatric phenomena, especially mood and anxiety symptoms, as well as completed suicide. Indeed, in acknowledgement of the potential for seasonal effects in depressive disorders, the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition indicates the specifier, "with seasonal pattern." However, the explanations for the relationships between seasonal changes and exacerbations of psychopathology remain unclear, although the empirical literature indicates that an association between sunshine and serotonin is likely. Given that the relationship between sunshine and serotonin is probably a multimediated phenomenon, one contributory facet may be the role of sunshine on human skin. Human skin has an inherent serotonergic system that appears capable of generating serotonin. In this edition of The Interface, we discuss the relationships among psychopathology, sunshine, serotonin, and the skin.