The influence of sunlight exposure on hospitalization in emergency psychiatry

Environmental conditions during early life may affect individual vulnerability to both physiological changes as well as psychiatric conditions, especially in those with a genetic susceptibility. Among all factors, sunlight exposure intensity has a crucial effect on affecting circadian functions high-risk individuals. A potential explanation of this relation is that excessive sunlight exposure is able to impair biological mechanisms, possibly through the dysregulation of serotonin and/or melatonin production/metabolism. The aim of this study was to evaluate the influence of excessive sunlight exposure in a sample of emergency psychiatry inpatients.

All subjects were consecutively recruited from the Psychiatric Inpatient Unit of San Luigi Gonzaga Hospital, Orbassano (University of Turin, Italy) from September 2013 to August 2015. Socio-demographic and clinical characteristics were carefully collected.

We initially screened a sample of 900 patients; however, only 730 subjects voluntary accepted to participate in the study. Patients with admissions in spring/summer (a period in which daylight/darkness ratio is longer) showed a higher prevalence of involuntary admission, an earlier age at illness onset, a longer duration of hospitalization and admission for (hypo)manic episode.

Excessive sunlight exposure may exert a fundamental role on psychopathological conditions presumably affecting biological vulnerability. A better understanding of its effect on the course of bipolar and other psychiatric disorders may assist in tailoring the adequate treatment for patients resulting in a shorter stay within hospitalized settings and a better treatment response.