Association between differences in ambient light exposure by hospital bed location and depressive symptoms among postpartum women.

Introduction: Environmental light is associated with the presence of depressive symptoms in healthy individuals, major depression, and postpartum depression. We hypothesized that women for delivery assigned to window-side beds (window-side group: WG) may exhibit lower levels of depressive symptoms at discharge than those assigned to corridor-side beds (corridor-side group: CG). Methods: This retrospective study involved postpartum women who were hospitalized for delivery in the obstetric ward of Oita University Hospital. We analyzed data of the Japanese version of the Edinburgh Postnatal Depression Scale (EPDS) assessed within approximately 1 week after delivery (within 7-days EPDS) and at an outpatient visit approximately 1 month after delivery (1-month EPDS). Analysis of covariance and binomial logistic regression analyses were conducted to evaluate between-group differences in EPDS scores and in the proportion of participants with EPDS scores of 9 or higher adjusting for relevant covariates. Pearson's correlation analysis was used to assess the relationship between within 7-days and 1-month EPDS scores. Results: A significant between-group difference was observed for within 7-day EPDS scores, with mean scores of 3.4 and 5.0 in the WG and CG, respectively. In the binomial logistic regression analysis of within 7-days EPDS, bed location and cesarean delivery were significant in the final model. No significant between-group difference was observed in 1-month EPDS. A significant positive correlation was observed between the within 7-days and 1-month EPDS scores. Discussion: These findings suggest that increasing exposure to ambient light during hospitalization for delivery may help reduce depressive symptoms.