The influence of light on suicidality: A narrative review

Suicide is a complex and deeply troubling phenomenon that occurs across all cultures and societies, representing a significant international public health challenge. Recent research has revealed a wide spectrum of ways light influences our brain circuits, with effects ranging from sleep-wake rhythm to mood regulation. Furthermore, a growing body of evidence highlights that light exposure is vital for both our physical and psychological well-being. In this paper, we hypothesize that light has an influence on suicidality. We examine evidence from several key areas: (1) currently available light-based treatments and suicide prevention measures; (2) the relationship between suicide rates and seasons; (3) the relationship between suicide rates and the time of day; and (4) the relationship between suicide rates and sunlight exposure. Based on the findings from studies exploring these topics, we propose a neurochemical model involving serotonin as a possible mediator of the relationship between light and suicide. A deeper understanding of the link between light and suicide could lead to a better identification of individuals at risk and potentially to the development of new, light-related suicide prevention measures.